Biomaterials in orthopaedics & trauma
Post on 22-Aug-2014
269 Views
Preview:
DESCRIPTION
Transcript
Biomaterials in Orthopaedics amp Trauma
Zahid Askar FCPS(Ortho) FRCS (Ortho)
Prof of Orthopaedics amp TraumaKhyber Medical College Peshawer
Study of Biomaterials
The physical and biological study of materials and their interactions with the biological environment
Increase use of biomaterials -Their interactions-Increasing Duration and stresses
Biomechanics
bull The science of movement of a living body including how muscles bones tendons and ligaments work together to produce movement
Response to Load
bull Force applied will lead to deformation and if continued beyond a certain point will lead to ultimate failure
bull The force ----- STRESS and Deformation is known as
STRAIN
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Study of Biomaterials
The physical and biological study of materials and their interactions with the biological environment
Increase use of biomaterials -Their interactions-Increasing Duration and stresses
Biomechanics
bull The science of movement of a living body including how muscles bones tendons and ligaments work together to produce movement
Response to Load
bull Force applied will lead to deformation and if continued beyond a certain point will lead to ultimate failure
bull The force ----- STRESS and Deformation is known as
STRAIN
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Biomechanics
bull The science of movement of a living body including how muscles bones tendons and ligaments work together to produce movement
Response to Load
bull Force applied will lead to deformation and if continued beyond a certain point will lead to ultimate failure
bull The force ----- STRESS and Deformation is known as
STRAIN
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Response to Load
bull Force applied will lead to deformation and if continued beyond a certain point will lead to ultimate failure
bull The force ----- STRESS and Deformation is known as
STRAIN
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull Force applied will lead to deformation and if continued beyond a certain point will lead to ultimate failure
bull The force ----- STRESS and Deformation is known as
STRAIN
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Stress amp Strain
Stress- Force per unit areaUnits NMSq M or Pascal
Strain- Change in length per unit original length
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Stress
Strain
Elastic Plastic
Yield Stress
Ultimate Stress
Breaking Stress
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
The path to failure
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
TENSILE STRENGTH ULTIMATE TENSILE STRENGTH - The maximum stress on the curve before breakage (NM2)
YIELD STRESS-
Point at which elastic behaviour changes to plastic behaviour
BREAKING STRESS
Point at which the substance failsbrakes
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Youngrsquos modulus E
bull Stress Strain For elastic part of curve or the
slope of the elastic part of the curve SI unit = pascal (Pa or Nm2 or mminus1middotkgmiddotsminus2) megapascals (MPa or Nmm2) or
gigapascals (GPa or kNmm2)
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull DUCTILITY BRITTLENESS- The amount by which a material deforms (ie the strain that occurs) before it breaks
Represented by age elongation or reduction in cross section
bull HARDNESS- The ability of the surface of a material to withstand forces
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull The Yield Point = marks the onset of plastic deformation
bull Plastic Region = Beyond the yield point irreversible (plastic) deformation takes place
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Elastic Modulus of Common Materials in Orthopaedics
bull Stainless Steel 200bull Titanium 100bull Cortical Bone 7-21bull Bone Cement 25-35bull Cancellous Bone 07-49bull UHMWPE 14-42
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Relative values of Youngs modulus of elasticity (numbers correspond to numbers on illustration to right)1Ceramic (Al2O3)2Alloy (Co-Cr-Mo)3Stainless steel4Titanium 5Cortical bone6Matrix polymers7PMMA8Polyethylene9Cancellous bone10Tendon ligament11Cartilage
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Bone Mechanicsbull Bone Density
ndash Subtle density changes greatly changes strength and elastic modulus
bull Density changesndash Normal agingDiseaseUseDisuse
Figure from Browner et al Skeletal Trauma 2nd Ed Saunders 1998
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Bone Biomechanics
bull Bone is anisotropic - its modulus is dependent upon the direction of loadingBone Type Load Type
Elastic Modulus
(times10 E9 Nm2)
Ultimate Stress
(times 10 E6 Nm2)Cortical Tension 114-191 107-146
Compression 151-197 156-212Shear 73-82
Cancellous Tension ~02-50 ~3-20Compression 01-3 15-50Shear 66 +- 17
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Material UltimateStrength
Tensile (MPa)
UltimateStrength
Compressive(MPa)
YieldStrength
02 Offset(MPa)
ElasticModulus
(MPa)
Cortical bone 100 175 80 15000
Cancellous bone 2 3 1000
Polyethylene 40 20 20 1000
PTFE Teflon 25 500
Acrylic bone cement 40 80 2000
Stainless steel (316 L) (annealed)
gt500 gt200 200000
Titanium (Al-4V) (alloy F 136)
900 800 100000
Cobalt chrome (wrought cold work)
1500 1000 230000
Super alloys (CoNiMo)
1800 1600 230000
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
ORTHOPAEDIC BIOMATERIALS
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
BIOMATERIAL -A non-viable material used in a medical device intended to interact with biological systems
State of Mutual Coexistance between a Biomaterial and the Physiological Environment Such as Neither has an Undesirable Effect on the Other
BIOCOMPATIBILITY
No host response to the materialBIOINERT
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Ideal Biomaterial
bull Suitable mechanical properties to fulfil its intended function
bull Must not corrode in biologic environmentbull Must not release potentially harmful
degradation by-products locally and systemically
bull To permit fabrication in the optimum design configuration
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Ideal Biomaterial
bull Be like the natural and mimic its biomechanical properties
bull Not elicit a response- Bioinertbull Elicit a favourable response- Biocompatiblebull Economical and Reproducible
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Implants- Uses
bull Helpbull Substitution
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
1048698
Mechanical Properties of Bone
bull Youngrsquos Modulus(E) 170 GNm2bull Ultimate Tensile Strength (UTS)
0132GNm2bull Compressive Strength(σc) 0192 GNm2bull Shear Modulus(K) 201 GNm2bull Poissonrsquos Ratio(ν) 03
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Materials used in Orthopaedicsbull Metals -Stainless Steel 316L -Co-Cr-Mo -Ti-6AL-4VCeramics- AluminaZirconiumPolymers- UHWPE PMMA SiliconesPEEK
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Stainless steel-(316L)
bull Iron- 60 bull Chromium- 20 bull Nickel- 14 bull Molybdenum- 3bull Carbon- 003 bull Manganese SiliconPS- 3
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Functions
bull Ironbull ChromiumNickel
Molybdenum-bull Carbon-bull Manganese Silicon -
bull Strengthbull Corrosionbull Strengthbull Manufacturing
Problems
The chromium forms an oxide layer when dipped in nitric acid to reduce corrosion and the molybdenum increases this protection when compared to other steels
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Stainless Steel
bull Strong bull Cheap bull Relatively ductile bull Relatively biocompatible
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull High Youngrsquos modulus ndash 200 GPascals (10 that of bone)
bull Leads to stress shielding of surrounding bone which can cause bone resorption
bull susceptible to corrosion
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Titanium and its alloys
bull Ti 6AL-4V ELI (Grade 23) bull Ti 6Al-4V (Grade 5) bull Excellent resistance to corrosion bull Youngrsquos modulusbull Stronger than stainless steels bull MRI complaint
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Disadvantagesopoor resistance to
wear o Can be brittle ie less
ductilegenerates more
metal debris than cobalt chrome
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
bull COBALT-BASED ALLOYSTwo main types of cobalt-based alloys
bull A cast alloy bull A wrought alloy bull Also known as Vitallium (or in Britain Stellite) is
often applied to both alloys
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Advantagesstrength and corrosion resistance
high abrasion resistance Superior to stainless steel
DisadvantagesMore expensive to
manufacturecannot be
contoured at the time of surgery
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
USES
bull Usually for bearing surfacesbull THRbull Metal-on-metal devices
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Material Elastic Yield UTensile Modulus Strength Strength
(GNm2) (MNm2) (MNm2)
316L 200 795 965 Co-Cr-Mo 210 950 1450Ti-6Al-4V 105 895 1173
Mechanical Properties of Orthopaedic Alloys
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
POLYMETHYLMETHACRYLATE (PMMA)
bull Prepolymerized methylmethacrylate( powder)bull Liquid monomer bull Exothermic Reactionbull 10 min at 23 0 C bull 60 0 C in the center of the material and 40 0 C
at the surfacebull A grouting agentbull Good in compressionbull Hard but brittle
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull 2 component materialbull Powder
bull polymerbull benzoyl peroxide (initiator)bull barium sulfate (radio-opacifier)
bull Liquidbull monomerbull DMPT (accelerator) NN-Dimethyl
-p-toluidinebull hydroquinone (stabilizer)
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
The curing process is divided into 4 stages a) mixing
The mixing can be done by hand or with the aid of centrifugation or vacuum technologiesb) stickywaitingc) working and d) hardening
It is recommended that the unopened cement components are stored at 73 degF (23 degC) for a minimum of 24 h before use
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
First generation cementing technique1)- Hand mixing 2)-Minimal preparation of the femoral canal 2)-Digital application of cement
Second generation cementing techniques1)-Preparation packing and drying of the femoral canal 2)-Distal cement restrictor 3)-Pulsatile irrigation 4)-Retrograde insertion of cement with a cement gun
Third generation cementing techniques1)-Cement is prepared using a vacuum-centrifugation( reduces porosity) 2)-The femoral canal is irrigated with pulsatile lavage and then packed with adrenaline soaked swabs 3)-Insertion and pressurisation of the cement in a retrograde fashion
Fourth generation cementing techniques Insertion using distal and proximal centralizers to ensure an even cement mantle (4th generation)
Generations of Cementing Technique
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
First Second Third FourthHand Mix with Spatula Hand mix with cement
gunVacuum centrifuge Mixing
Third with
Leave Cancellous Bone
Remove bone from the endoesteal surface
Remove bone from the endoesteal surface
PROXIMAL amp DISTAL CENTRALISER
Vent Femoral canal Distal Cement restrictor
Distal Cement restrictor
Minimal canal Preparation
Brush Pulsatile irrigation
Brush Pulsatile irrigation
Irrigate amp Suck femoral canal
Irrigation Pack and dry
Irrigation Pack with adrenaline gauze and dry
Manual Insertion of the Dough
Cement Gun Insertion Cement Gun Insertion amp pressuriation
Manual Insertion of the stem
Manual Position of the Stem
Manual Position of the Stem
FEmoral stem shapes Improved Femur Design
Surface texturing and contouring
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
USESused for fixation and load distribution in conjunction with orthopeadic implantsFunctions by interlocking with bone
bull May be used to fill tumor defects and minimize local recurrence
Advantages1)-Reaches ultimate strength at 24 hours2)-Strongest in compression3)-Youngs modulus between cortical and cancellous bone
Disadvantagesbull poor tensile and shear strengthbull insertion can lead to
dangerous drop in blood pressure
bull failure often caused by microfracture and fragmentation
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Ceramic
bull A ceramic material may be defined as any inorganic crystalline material compounded of a metal and a non-metal
bull Aluminabull Zirconia
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Advantages1)-best wear characteristics with PE2)-high compressive strength
Disadvantages1)-typically brittle low fracture toughness 2)-high Youngs modulus3)-Low tensile strength4)-Poor crack resistance characteristics
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Ultra-high-molecular-weight polyethylene ( UHMWPE)
bull Sterilised by Gamma irradiation bull Increases polymer chain cross-linking
which improves wear characteristicsbull Decreases fatigue and fracture resistance
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Advantages1)-Tough2)-Ductile3)-Resilient4)-Resistant to wear
Disadvantages1)-Susceptible to abrasion2)-Wear usually caused by third body inclusions3)-Thermoplastic (may be altered by extreme temperatures)weaker than bone in tension
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Silicones
ndash Polymers that are often used for replacement in non-weight bearing joints
ndash Disadvantagesbull poor strength and wear capability responsible for
frequent synovitis
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Polyether ether ketone (PEEK) is a colourless organic thermoplastic polymer in the polyaryletherketone (PAEK) family used in engineering applications
Shape-memory polymers (SMPs) are polymeric smart materials that have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus (trigger) such as temperature change
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Polyetheretherketone or PEEK was originally developed in the late 1970s by the US aerospace industry which was taken by its properties of stability at high temperatures and thus its potential for high-load high-temperature applications In the late 1990s a highly pure and implantable grade of PEEK known as PEEK-OPTIMA was commercialised by Invibio Biomaterial Solutions and subsequently embraced by the medical device industry
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Angle stable interlocking screws which have a sleeve that expands to fit tightly within the nail interlock to improve construct stability of intramedullary nailing of distal tibia fractures
Angle stable interlocking screws
Horn J Linke B Houmlntzsch D Gueorguiev B Schwieger K Angle stable interlocking screws improve construct stability of intramedullary nailing of distal tibia fractures A biomechanical studyInjury 200940[7]767-771)
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
How do Materials fail
bull Corrosionbull Fatiguebull Wear
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Corrosion
bull A chemical reaction in which material is removed from an object
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Galvanic corrosion- due to two different metals being used eg stainless steel screws and titanium plate
Stress corrosion- The presence of a crack due to stress
Crevice corrosion fretting occurs where components have a relative movement against one another
Pit corrosion- A local form of crevice corrosion due to abrasion produces a pit
Types Of Corrosion
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Fatigue-
bull Progressive failure of a material due to the application of cyclical stresses below the ultimate stress of the material causing failure
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
bull All implants will eventually break if the fracture does not heal
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Basic Biomechanics
bull Load to Failurendash Continuous application
of force until the material breaks (failure point at the ultimate load)
ndash Common mode of failure of bone and reported in the implant literature
bull Fatigue Failurendash Cyclical sub-
threshold loading may result in failure due to fatigue
ndash Common mode of failure of orthopaedic implants and fracture fixation constructs
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Wear
bull The removal of material from solid surfaces by mechanical action
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
Interfacial wear - when bearing surfaces come into direct contact can occur in 2 ways 1 Adhesive wear when surface fragments adhere to each other and are torn from the surface during sliding 2 Abrasive wear when a soft material is scraped by a harder material
Third Body Wear
Corrosion Wear
Fatigue Wear due to accumulation of microscopic damage within the bearing material due to repetitive cyclical stressing
Types Of Wear
- Biomaterials in Orthopaedics amp Trauma
- Study of Biomaterials
- Biomechanics
- Response to Load
- Slide 5
- Stress amp Strain
- Slide 7
- The path to failure
- Slide 9
- Youngrsquos modulus E
- Slide 11
- Slide 12
- Slide 13
- Elastic Modulus of Common Materials in Orthopaedics
- Slide 15
- Slide 16
- Slide 17
- Bone Mechanics
- Slide 19
- Bone Biomechanics
- Slide 21
- ORTHOPAEDIC BIOMATERIALS
- Slide 23
- Ideal Biomaterial
- Ideal Biomaterial
- Implants- Uses
- 1048698 Mechanical Properties of Bone
- Materials used in Orthopaedics
- Stainless steel-(316L)
- Functions
- Stainless Steel
- Slide 32
- Titanium and its alloys
- Slide 34
- Slide 35
- Cobalt-Chromium-Molybdenum alloy (Co-Cr-Mo)
- Slide 37
- Slide 38
- USES
- Slide 40
- Mechanical Properties of Orthopaedic Alloys
- POLYMETHYLMETHACRYLATE (PMMA)
- Slide 43
- Slide 44
- Slide 45
- Slide 46
- Slide 47
- Slide 48
- Slide 49
- Ceramic
- Slide 51
- Slide 52
- Ultra-high-molecular-weight polyethylene ( UHMWPE)
- Slide 54
- Silicones
- Slide 56
- Slide 57
- Slide 58
- Slide 59
- Slide 60
- Slide 61
- Slide 62
- How do Materials fail
- Corrosion
- Slide 65
- Fatigue-
- Slide 67
- Basic Biomechanics
- Wear
- Slide 70
top related