Fractures and Bone Healing H Biology II Adapted 2014-2015.

Fractures and Fractures and Bone HealingBone Healing

H Biology IIH Biology IIAdapted 2014-2015Adapted 2014-2015

Response to Mechanical StressResponse to Mechanical Stress

Wolff’s law – a bone grows or remodels in Wolff’s law – a bone grows or remodels in response to the forces or demands placed response to the forces or demands placed upon itupon it

Observations supporting Wolff’s law Observations supporting Wolff’s law includeinclude Long bones are thickest midway along the Long bones are thickest midway along the

shaft (where bending stress is greatest)shaft (where bending stress is greatest) Curved bones are thickest where they are Curved bones are thickest where they are

most likely to bucklemost likely to buckle

Response to Mechanical StressResponse to Mechanical Stress

Trabeculae form along lines of stressTrabeculae form along lines of stress Large, bony projections occur where Large, bony projections occur where

heavy, active muscles attachheavy, active muscles attach

Response to Mechanical StressResponse to Mechanical Stress

StatisticsStatistics

Fractures of extremities most commonFractures of extremities most common More common in men up to 45 years of ageMore common in men up to 45 years of age More common in women over 45 years of ageMore common in women over 45 years of age Before 75 years wrist fractures (Colles’) most Before 75 years wrist fractures (Colles’) most

commoncommon After 75 years hip fractures most commonAfter 75 years hip fractures most common

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FracturesFractures

A A fracturefracture is any break in a bone. is any break in a bone. Fracture repair involves formation of a clot called Fracture repair involves formation of a clot called

a a fracture hematomafracture hematoma, organization of the , organization of the fracture hematoma into granulation tissue called fracture hematoma into granulation tissue called a a procallusprocallus (subsequently transformed into a (subsequently transformed into a fibrocartilaginousfibrocartilaginous [soft] [soft] calluscallus), conversion of the ), conversion of the fibrocartilaginous callus into the spongy bone of fibrocartilaginous callus into the spongy bone of a a bonybony (hard) (hard) calluscallus, and, finally, remodeling of , and, finally, remodeling of the callus to nearly original form.the callus to nearly original form.

Bone Fractures (Breaks)Bone Fractures (Breaks)

Bone fractures are classified by:Bone fractures are classified by: The position of the bone ends after fractureThe position of the bone ends after fracture The completeness of the breakThe completeness of the break The orientation of the bone to the long axisThe orientation of the bone to the long axis Whether or not the bones ends penetrate the Whether or not the bones ends penetrate the

skinskin

Common Types of FracturesCommon Types of Fractures

Magnitude and direction of force are Magnitude and direction of force are determining factors in type of fracture.determining factors in type of fracture.

ClosedClosed – – Bone fragments do not pierce skinBone fragments do not pierce skin Open/compoundOpen/compound – – Bone fragments pierce skinBone fragments pierce skin Displaced or undisplacedDisplaced or undisplaced

Common Types of FracturesCommon Types of Fractures

Comminuted – bone fragments into three Comminuted – bone fragments into three or more pieces; common in the elderlyor more pieces; common in the elderly

Spiral – ragged break when bone is Spiral – ragged break when bone is excessively twisted; common sports injuryexcessively twisted; common sports injury

Depressed – broken bone portion pressed Depressed – broken bone portion pressed inward; typical skull fractureinward; typical skull fracture

Compression – bone is crushed; common Compression – bone is crushed; common in porous bonesin porous bones

Common Types of FracturesCommon Types of Fractures

Epiphyseal – epiphysis separates from Epiphyseal – epiphysis separates from diaphysis along epiphyseal line; occurs diaphysis along epiphyseal line; occurs where cartilage cells are dyingwhere cartilage cells are dying

Greenstick – incomplete fracture where Greenstick – incomplete fracture where one side of the bone breaks and the other one side of the bone breaks and the other side bends; common in childrenside bends; common in children

Common Types of FracturesCommon Types of Fractures

Common Types of FracturesCommon Types of Fractures

Common Types of FracturesCommon Types of Fractures

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Common Types of FracturesCommon Types of Fractures

Named for shape or position of fracture lineNamed for shape or position of fracture line Common types of fractureCommon types of fracture

Pott’s -- distal fibular fracturePott’s -- distal fibular fracture Colles’s -- distal radial fractureColles’s -- distal radial fracture stress fracture -- microscopic fissures from stress fracture -- microscopic fissures from

repeated strenuous activitiesrepeated strenuous activities

Transverse fractureTransverse fracture

Usually caused by directly applied force to Usually caused by directly applied force to fracture sitefracture site

Spiral (Oblique)Spiral (Oblique)

Caused by violence transmitted through Caused by violence transmitted through limb from a distance (twisting movements)limb from a distance (twisting movements)

GreenstickGreenstick

Occurs in children: bones soft and bend Occurs in children: bones soft and bend without fracturing completelywithout fracturing completely

Compression (Crush) fracturesCompression (Crush) fracturesFracture in cancellous bone: result of Fracture in cancellous bone: result of compression (osteoporosis)compression (osteoporosis)

Burst fractureBurst fractureOccurs in short bones, e.g. vertebra from Occurs in short bones, e.g. vertebra from

strong direct pressure such as impaction strong direct pressure such as impaction of disc.of disc.

Avulsion fractureAvulsion fracture Caused by traction, bony fragment usually torn off by a Caused by traction, bony fragment usually torn off by a

tendon or ligament.tendon or ligament. What muscle group attaches to this bony prominence What muscle group attaches to this bony prominence

and what nerve also runs in close proximity?and what nerve also runs in close proximity? Forearm flexors (common flexor origin) ulnar nerveForearm flexors (common flexor origin) ulnar nerve

Fracture dislocation/subluxationFracture dislocation/subluxationFracture involves a joint: results in Fracture involves a joint: results in

malalignment of joint surfaces.malalignment of joint surfaces.

Impacted fractureImpacted fracture

Bone fragments are impacted into each Bone fragments are impacted into each other.other.

Comminuated fractureComminuated fracture

Two or more bone pieces - high energy Two or more bone pieces - high energy traumatrauma

Comminuated fractures can require Comminuated fractures can require serious hardware to repair.serious hardware to repair.

Stress FractureStress Fracture

Abnormal stress on normal bone (fatigue Abnormal stress on normal bone (fatigue fracture) or normal stress on abnormal fracture) or normal stress on abnormal bone (insufficiency fracture).bone (insufficiency fracture).

Functions of the X-rayFunctions of the X-ray

Localizes fracture and number of fragmentsLocalizes fracture and number of fragments Indicates degree of displacementIndicates degree of displacement Evidence of pre-existing disease in boneEvidence of pre-existing disease in bone Foreign bodies or air in tissuesForeign bodies or air in tissues May show other fracturesMay show other fractures MRI, CT or ultrasound to reveal soft tissue MRI, CT or ultrasound to reveal soft tissue

damagedamage

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Repair/Healing of BoneRepair/Healing of Bone Healing is faster in bone than in cartilage due to Healing is faster in bone than in cartilage due to

lack of blood vessels in cartilagelack of blood vessels in cartilage Healing of bone is still slow process due to Healing of bone is still slow process due to

vessel damagevessel damage Clinical treatmentClinical treatment

closed reduction = restore pieces to normal position closed reduction = restore pieces to normal position by manipulationby manipulation

open reduction = realignment during surgeryopen reduction = realignment during surgery

How to Handle FracturesHow to Handle Fractures

ReductionReduction Open reductionOpen reduction

– – Allows very accurate reductionAllows very accurate reduction

– – Risk of infectionRisk of infection

– – Usually when internal fixation is Usually when internal fixation is neededneeded

ManipulationManipulation

– – Usually with anesthesiaUsually with anesthesia TractionTraction

– – Fractures or dislocation requiring slow therapyFractures or dislocation requiring slow therapy

Fracture FixationFracture Fixation

4-12 weeks4-12 weeks External fixationExternal fixation Internal fixationInternal fixation

Intermedually nails, compression platesIntermedually nails, compression plates Frame fixationFrame fixation

External fixationExternal fixation

Used for fractures that are too unstable for Used for fractures that are too unstable for a cast. You can shower and use the hand a cast. You can shower and use the hand gently with the external fixator in place.gently with the external fixator in place.

Frame fixationFrame fixation

Allows correction of deformities by moving Allows correction of deformities by moving the pins in relation to the frame.the pins in relation to the frame.

Internal fixationInternal fixation

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Repair of Repair of a a

FractureFracture

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFractureHematoma Hematoma

formationformationTorn blood vessels Torn blood vessels

hemorrhagehemorrhageA mass of clotted A mass of clotted

blood (hematoma) blood (hematoma) forms at the forms at the fracture sitefracture site

Site becomes Site becomes swollen, painful, swollen, painful, and inflamedand inflamed

3-4 hours3-4 hours

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Hematoma

Hematoma formation

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFracture

The fibrocartilaginous callus forms when:The fibrocartilaginous callus forms when:Osteoblasts and fibroblasts migrate to the Osteoblasts and fibroblasts migrate to the

fracture and begin reconstructing the bonefracture and begin reconstructing the boneFibroblasts secrete collagen fibers that Fibroblasts secrete collagen fibers that

connect broken bone endsconnect broken bone endsOsteoblasts begin forming spongy boneOsteoblasts begin forming spongy boneOsteoblasts furthest from capillaries secrete Osteoblasts furthest from capillaries secrete

an externally bulging cartilaginous matrix that an externally bulging cartilaginous matrix that later calcifieslater calcifies

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFractureFibrocartilaginoFibrocartilagino

us callus formsus callus formsGranulation Granulation

tissue (soft tissue (soft callus) forms a callus) forms a few days after few days after the fracturethe fracture

Capillaries grow Capillaries grow into the tissue into the tissue and phagocytic and phagocytic cells begin cells begin cleaning debriscleaning debris

2 Fibrocartilaginous callus formation

External callus

New blood vessels

Spongy bone trabeculae

Internal callus (fibrous tissue and cartilage)

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFracture

Bony callus formationBony callus formationNew bone trabeculae New bone trabeculae

appear in the appear in the fibrocartilaginous callusfibrocartilaginous callus

Fibrocartilaginous callus Fibrocartilaginous callus converts into a bony converts into a bony (hard) callus(hard) callus

Bone callus begins 3-4 Bone callus begins 3-4 weeks after injury, and weeks after injury, and continues until firm union continues until firm union is formed 2-3 months is formed 2-3 months laterlater

3 Bony callus formation

Bony callus of spongy bone

Stages in the Healing of a Bone Stages in the Healing of a Bone FractureFracture

Bone remodelingBone remodelingExcess material on Excess material on

the bone shaft the bone shaft exterior and in the exterior and in the medullary canal is medullary canal is removedremoved

Compact bone is Compact bone is laid down to laid down to reconstruct shaft reconstruct shaft wallswalls 4 Bone remodeling

Healing fracture