Lesson 03

Copyright © 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc.

LessonLesson 3 3

Kinematics of TraumaKinematics of Trauma

Copyright © 2007, 2003 by Mosby, Inc., an affiliate of Elsevier Inc. Slide 2

ObjectivesObjectives

As a result of active participation in this As a result of active participation in this lesson you should be able to:lesson you should be able to: Apply principles of kinematics to create an index of Apply principles of kinematics to create an index of

suspicion for blunt and penetrating traumasuspicion for blunt and penetrating trauma Incorporate principles of kinematics into an overall Incorporate principles of kinematics into an overall

impression of the patient’s needs for intervention impression of the patient’s needs for intervention and transportand transport

Consider the interaction of age and health Consider the interaction of age and health

status with kinematics to modify the index status with kinematics to modify the index

of suspicion for injuryof suspicion for injury


IntroductionIntroduction

Applying principles of kinematics to patient Applying principles of kinematics to patient assessment helps predict injuries that might assessment helps predict injuries that might otherwise be missedotherwise be missed

Failure to suspect injuries based on Failure to suspect injuries based on kinematics can have dire impact on a kinematics can have dire impact on a patient’s outcomepatient’s outcome


OverviewOverview

General principles of kinematicsGeneral principles of kinematics Mechanical components of energy exchangeMechanical components of energy exchange

Blunt and penetrating mechanismsBlunt and penetrating mechanisms Regional injury pathophysiologyRegional injury pathophysiology

Blunt and penetrating mechanismsBlunt and penetrating mechanisms


General Principles of KinematicsGeneral Principles of Kinematics

A crash is any impact between the body and A crash is any impact between the body and an objectan object

Assessment and management of the injured Assessment and management of the injured patient must consider three phasespatient must consider three phases PrecrashPrecrash CrashCrash PostcrashPostcrash



Precrash factors must be considered in the Precrash factors must be considered in the assessment and management of the trauma assessment and management of the trauma patientpatient Patient age and sizePatient age and size Drugs/alcoholDrugs/alcohol Preexisting medical conditions and medicationsPreexisting medical conditions and medications



CrashCrash Three impacts occur in an Three impacts occur in an

automobile crashautomobile crash In falls and other In falls and other

mechanisms, only two mechanisms, only two crashes are involvedcrashes are involved

Consideration of:Consideration of:• Direction of energy Direction of energy

exchangeexchange

• Amount of energy Amount of energy exchangeexchange

• Effect on the bodyEffect on the body



PostcrashPostcrash Patient outcome is affected by conditions after Patient outcome is affected by conditions after

the crashthe crash• Response time and resources availableResponse time and resources available

• Providers’ knowledge of kinematics, assessment, and Providers’ knowledge of kinematics, assessment, and managementmanagement

Providers’ response depends on knowledge of Providers’ response depends on knowledge of energy and anatomyenergy and anatomy



EnergyEnergy What were the crash phase factors?What were the crash phase factors?

• DirectionDirection

• SpeedSpeed

• Stopping timeStopping time

• Restraint systems and protective gearRestraint systems and protective gear

• EjectionEjection

Surveying the scene to predict injury patterns Surveying the scene to predict injury patterns produced by crash factors is called produced by crash factors is called kinematicskinematics



Newton’s first law of Newton’s first law of motionmotion A body at rest will remain A body at rest will remain

at rest and a body in at rest and a body in motion will remain in motion will remain in motion unless acted upon motion unless acted upon by an outside forceby an outside force

Three impacts in MVCs Three impacts in MVCs revisitedrevisited



The law of The law of conservation of conservation of energyenergy Energy can be Energy can be

neither created nor neither created nor destroyeddestroyed——only only changed in formchanged in form

Heat, noise, Heat, noise, vehicle vehicle deformation, tissue deformation, tissue damagedamage



Kinetic energyKinetic energy½ (mass) (velocity½ (mass) (velocity22))

150-lb (68-kg) person travels 150-lb (68-kg) person travels

at 30 mph (48 kph)at 30 mph (48 kph)

KE units = (150/2) (30KE units = (150/2) (3022) = 67,500) = 67,500



Mass vs. velocityMass vs. velocity

KE = (160/2) (30KE = (160/2) (3022) = 72,000 units) = 72,000 units

KE = (150/2) (40KE = (150/2) (4022) = 120,000 units) = 120,000 units



ForceForceMass Mass ×× acceleration = force acceleration = force

= mass = mass ×× deceleration deceleration

Stopping distance matters!Stopping distance matters!


General Principles of KinematicsGeneral Principles of KinematicsAcceleration = (vAcceleration = (vfinal final − − vvoriginaloriginal)/time, expressed as m/sec)/time, expressed as m/sec22 or km/hr or km/hr22

Example:Example:A vehicle traveling 70 kph (1167 m/sec or 43 mph) brakes and comes to a stop over 7 sec.A vehicle traveling 70 kph (1167 m/sec or 43 mph) brakes and comes to a stop over 7 sec.

(0 – 1167)/7 = (0 – 1167)/7 = −−167 m/sec167 m/sec22

A vehicle traveling 70 kph strikes a bridge abutment and comes to a stop over 0.5 sec.A vehicle traveling 70 kph strikes a bridge abutment and comes to a stop over 0.5 sec.

(0 – 1167)/0.5 = (0 – 1167)/0.5 = −−2334 m/sec2334 m/sec22



Force (in Newtons) = mass Force (in Newtons) = mass ×× acceleration acceleration

Example:Example:907-kg (2000-lb) vehicle traveling at 70 kph907-kg (2000-lb) vehicle traveling at 70 kph

with a stopping time of 7 sec.with a stopping time of 7 sec.

907 907 ×× −−167 = 167 = −−151,469151,469

907-kg (2000-lb) vehicle traveling at 70 kph 907-kg (2000-lb) vehicle traveling at 70 kph with a stopping time of 0.5 sec.with a stopping time of 0.5 sec.

907 907 ×× −−2334 = 2334 = −−2,116,9382,116,938



Energy exchangeEnergy exchange The greater the density of an object or body The greater the density of an object or body

tissue, the greater the number of particles tissue, the greater the number of particles impacted by a forceimpacted by a force• The less dense of 2 objects will receive more damage The less dense of 2 objects will receive more damage

(deformation)(deformation)

The greater the contact area, the greater the The greater the contact area, the greater the number of particles impacted by a forcenumber of particles impacted by a force



Energy exchangeEnergy exchange Body tissue densitiesBody tissue densities

• Air (lung)Air (lung)

• Water (muscles, organs)Water (muscles, organs)

• Solid (bone)Solid (bone)

How would each of these tissues How would each of these tissues be affected by the same force?be affected by the same force?



Energy exchange: CavitationEnergy exchange: Cavitation Transfer of kinetic energy to the tissues causes Transfer of kinetic energy to the tissues causes

tissue particles to accelerate away from the impact, tissue particles to accelerate away from the impact, leaving a cavityleaving a cavity• Temporary cavity (elasticity)Temporary cavity (elasticity)

• Permanent cavity (force exceeds tensile strength)Permanent cavity (force exceeds tensile strength)



Energy exchange: Object surface areaEnergy exchange: Object surface area Blunt trauma: energy applied over a larger surface Blunt trauma: energy applied over a larger surface

of the body results in less localized energy of the body results in less localized energy exchangeexchange

Penetrating trauma: energy concentrated to small Penetrating trauma: energy concentrated to small area of tissue with greater destructive force to one area of tissue with greater destructive force to one areaarea


ScenarioScenario

Your patient is a 37-year-old construction Your patient is a 37-year-old construction worker who fell 25 ft (7.6 m) from a scaffold worker who fell 25 ft (7.6 m) from a scaffold onto packed, dry, bare earth, making first onto packed, dry, bare earth, making first contact with outstretched arms.contact with outstretched arms. What factors impact the transfer of energy?What factors impact the transfer of energy? What injuries do you suspect?What injuries do you suspect? What is the expected severity of injuries?What is the expected severity of injuries?


Mechanical PrinciplesMechanical Principles

Blunt traumaBlunt trauma Severity and pattern depend onSeverity and pattern depend on

Direction of impactDirection of impact For vehicle crashesFor vehicle crashes——energy absorbed by vehicleenergy absorbed by vehicle Part(s) of body to which energy is transmittedPart(s) of body to which energy is transmitted Use of protective equipmentUse of protective equipment Compression, deceleration, accelerationCompression, deceleration, acceleration Density and contact area of objectDensity and contact area of object Velocity at impactVelocity at impact



Blunt trauma forcesBlunt trauma forces CompressionCompression

• Example: The heart is compressed Example: The heart is compressed between the sternum and spine upon between the sternum and spine upon sudden frontal impactsudden frontal impact



Blunt trauma forcesBlunt trauma forces ShearShear

• One part of a structure One part of a structure changes speed faster changes speed faster than another part of the than another part of the structurestructure

• Examples:Examples: Aortic arch at Aortic arch at

ligamentum ligamentum arteriosumarteriosum

Kidneys at renal arteryKidneys at renal artery


Mechanical PrinciplesMechanical Principles Motor vehicle Motor vehicle

crashescrashes Frontal impactFrontal impact Rear impactRear impact Lateral impactLateral impact Rotational impactRotational impact RolloverRollover Motorcycle Motorcycle

crashescrashes PedestrianPedestrian––motor motor

vehicle crashesvehicle crashes

QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

Click to play video



General principles of rapid deceleration General principles of rapid deceleration mechanisms (MVCs, falls, etc.)mechanisms (MVCs, falls, etc.) Three collisionsThree collisions

• Vehicle collides with object (MVCs only)Vehicle collides with object (MVCs only)

• Occupant strikes a surfaceOccupant strikes a surface

• Occupant’s internal organs collide with each other or the Occupant’s internal organs collide with each other or the wall of a body cavitywall of a body cavity



General principles of rapid deceleration General principles of rapid deceleration mechanisms (MVCs, falls, etc.)mechanisms (MVCs, falls, etc.) Car strikes tree, stopping at the point of impact, Car strikes tree, stopping at the point of impact,

but the rest of the car continues forward, causing but the rest of the car continues forward, causing deformation until the energy is dissipated by deformation until the energy is dissipated by deforming the cardeforming the car



General principles of rapid deceleration General principles of rapid deceleration mechanisms (MVCs, falls, etc.)mechanisms (MVCs, falls, etc.) The damage to a vehicle mirrors the injury pattern The damage to a vehicle mirrors the injury pattern

to the bodyto the body The unrestrained driver’s chest strikes the steering The unrestrained driver’s chest strikes the steering

wheel, stopping it at the point of impactwheel, stopping it at the point of impact The rest of the body continues forwardThe rest of the body continues forward Cavitation of the body is temporaryCavitation of the body is temporary



Motor vehicle crashes: frontal impactMotor vehicle crashes: frontal impact Damage indicates speed of vehicleDamage indicates speed of vehicle The greater the speed at impact, the greater the The greater the speed at impact, the greater the

intrusion into the body of the vehicleintrusion into the body of the vehicle Occupants move at the same speed as the vehicleOccupants move at the same speed as the vehicle



Motor vehicle Motor vehicle crashes: frontal crashes: frontal impactimpact Two pathways of the Two pathways of the

unrestrained/impropeunrestrained/improperly restrained rly restrained occupantoccupant• Up and overUp and over

• Down and underDown and underNational Highway Traffic Safety Administration Video



Click to play video


Mechanical PrinciplesMechanical Principles Up and overUp and over

Head leadsHead leads Compression of Compression of

cervical spinecervical spine Chest/abdomen Chest/abdomen

impacts steering impacts steering wheelwheel• Compression of Compression of

hollow and solid hollow and solid organsorgans

• ShearingShearing



Down and underDown and under Force is transmitted Force is transmitted

to lower extremitiesto lower extremities• Tibial impactTibial impact

• Femoral impactFemoral impact

Upper body rotates Upper body rotates forward and strikes forward and strikes dash or steering dash or steering wheelwheel


Mechanical Principles: Mechanical Principles: Rear ImpactRear Impact


Mechanical PrinciplesMechanical Principles Motor vehicle crashes: rear impactMotor vehicle crashes: rear impact

““Bullet vehicle” and target vehicleBullet vehicle” and target vehicle Energy of bullet vehicle is converted to damage Energy of bullet vehicle is converted to damage

and acceleration of target vehicleand acceleration of target vehicle Hyperextension of the neck may occur with Hyperextension of the neck may occur with

improperly placed/absent headrest improperly placed/absent headrest Rapid deceleration may follow if the target car Rapid deceleration may follow if the target car

strikes another object or brakesstrikes another object or brakes


Mechanical Principles: Lateral ImpactMechanical Principles: Lateral Impact


Mechanical PrinciplesMechanical Principles Motor vehicle crashes: Motor vehicle crashes:

lateral impactlateral impact Intersection collisionsIntersection collisions Rapid lateral acceleration Rapid lateral acceleration

and impact of door and impact of door against occupantagainst occupant• Compression of thorax and Compression of thorax and

thoracic organs, including thoracic organs, including overpressure injuriesoverpressure injuries

• Shear injury to aortaShear injury to aorta• Abdominal (spleen/liver) Abdominal (spleen/liver)

and pelvic injuriesand pelvic injuries• Cervical spine lateral Cervical spine lateral

flexion and rotationflexion and rotation• HeadHead

National Highway Traffic Safety Administration Video



Click to play video


Mechanical Principles: Mechanical Principles: Rotational ImpactRotational Impact



Click to play video



Motor vehicle crashes: rotational impactMotor vehicle crashes: rotational impact A corner of the vehicle stops, the rest of the A corner of the vehicle stops, the rest of the

vehicle continues in forward motion until energy vehicle continues in forward motion until energy

is transformedis transformed Combination of frontal and lateral patternsCombination of frontal and lateral patterns More severe injuries to victim closest to the point More severe injuries to victim closest to the point

of impactof impact


Mechanical Principles: RolloverMechanical Principles: Rollover



Click to play video



Motor vehicle crashes: rollover impactMotor vehicle crashes: rollover impact Multiple impacts at various anglesMultiple impacts at various angles Energy is exchanged at each impactEnergy is exchanged at each impact Restrained driverRestrained driver

• Body is fixed, but organs move (shearing)Body is fixed, but organs move (shearing)

Unrestrained driverUnrestrained driver• Partial or full ejectionPartial or full ejection

• Direct impact with ground, tree, etc.Direct impact with ground, tree, etc.

• Crushed by vehicleCrushed by vehicle



Motor vehicle crashesMotor vehicle crashes Unrestrained occupantsUnrestrained occupants

• Rollovers account for a small proportion of crashes but Rollovers account for a small proportion of crashes but a high proportion of ejection and deatha high proportion of ejection and death

• 75% of totally ejected occupants die75% of totally ejected occupants die

• Risk of death is 6 times greater for ejected occupantsRisk of death is 6 times greater for ejected occupants


Mechanical Principles: RestraintsMechanical Principles: Restraints



Motor vehicle crashesMotor vehicle crashes Restrained occupantsRestrained occupants

• Properly placed restraints Properly placed restraints allow absorption of energy allow absorption of energy by skeletal structures by skeletal structures resulting in few serious resulting in few serious injuriesinjuries

• Force of body is transmitted Force of body is transmitted to restraint systemsto restraint systems

• Injury is produced by Injury is produced by improperly placed improperly placed restraints/occupantsrestraints/occupants CompressionCompression OverpressureOverpressure

National Highway Traffic Safety Administration Video



Click to play video


ScenarioScenario

Your patient is a 52-year-old motorcyclist who Your patient is a 52-year-old motorcyclist who struck a guard rail nearly head-on as he was struck a guard rail nearly head-on as he was rounding a curve at a high rate of speed and rounding a curve at a high rate of speed and was ejected from the bike, landing in a grassy was ejected from the bike, landing in a grassy area beyond the guardrail. He was not area beyond the guardrail. He was not wearing a helmet.wearing a helmet. What injury patterns do you suspect?What injury patterns do you suspect?


Mechanical PrinciplesMechanical Principles Motorcycle crashesMotorcycle crashes

Laws of physics don’t Laws of physics don’t change, but interaction change, but interaction of the vehicle and of the vehicle and occupant differsoccupant differs


Motorcycle: EjectionMotorcycle: Ejection



Motorcycle crashes: head-onMotorcycle crashes: head-on Impact stops the vehicleImpact stops the vehicle Center of gravity is above and behind the front Center of gravity is above and behind the front

axle, making it the pivot pointaxle, making it the pivot point Rider is ejected over the handlebars; impacting Rider is ejected over the handlebars; impacting

thighsthighs Bilateral femur fractures are commonBilateral femur fractures are common Secondary impact with stationary object Secondary impact with stationary object

or groundor ground


Motorcycle: Angular ImpactMotorcycle: Angular Impact



Motorcycle crashes: angularMotorcycle crashes: angular Motorcycle strikes an object (vehicle, guardrail, Motorcycle strikes an object (vehicle, guardrail,

etc.) at an angleetc.) at an angle Motorcycle falls on occupant or occupant is Motorcycle falls on occupant or occupant is

crushed between the motorcycle and object struckcrushed between the motorcycle and object struck Extensive injuries to extremitiesExtensive injuries to extremities Abdominal injuriesAbdominal injuries


Motorcycle: Laying Down the BikeMotorcycle: Laying Down the Bike



Motorcycle crashes: ejectionMotorcycle crashes: ejection Injury occurs at point of impact and radiates Injury occurs at point of impact and radiates

throughout body as energy is transformedthroughout body as energy is transformed Laying down the bike can result in extensive skin Laying down the bike can result in extensive skin

damage in unprotected ridersdamage in unprotected riders



Motorcycle crashes: injury preventionMotorcycle crashes: injury prevention Helmets save livesHelmets save lives Incidence of head injuries is 300% higher without Incidence of head injuries is 300% higher without

helmetshelmets Helmets neither prevent nor contribute to neck Helmets neither prevent nor contribute to neck

injuriesinjuries Other protection includes boots and leather Other protection includes boots and leather

clothingclothing



PedestriansPedestrians Crash phases vary by height relative to Crash phases vary by height relative to

vehiclevehicle AdultsAdults

• Initial impact to lower extremities/hipsInitial impact to lower extremities/hips

• Torso rolls onto hoodTorso rolls onto hood

• Victim falls to ground, often head-firstVictim falls to ground, often head-first


Adult PatternAdult Pattern



Pedestrians: pediatricPedestrians: pediatric May turn toward vehicleMay turn toward vehicle Impact to thighs or pelvisImpact to thighs or pelvis Impact to thoraxImpact to thorax Head and face strike front or hood of vehicleHead and face strike front or hood of vehicle May not be thrown clear and may be drug by or May not be thrown clear and may be drug by or

run over by vehiclerun over by vehicle


Pediatric PatternPediatric Pattern



FallsFalls Falls from more than 3Falls from more than 3××

patient height are severepatient height are severe Velocity increases with Velocity increases with

heightheight Landing surface affects Landing surface affects

stopping distance stopping distance (deceleration)(deceleration)


Mechanical PrinciplesMechanical Principles FallsFalls

Feet-firstFeet-first• Energy absorption occurs vertically through lower Energy absorption occurs vertically through lower

extremities to spineextremities to spine• Compression occurs because of continued downward Compression occurs because of continued downward

movement of torso and headmovement of torso and head• Hyperflexion and compression injuries of spineHyperflexion and compression injuries of spine

Outstretched armsOutstretched arms• Colles’ fractures, clavicle fractures, shoulder Colles’ fractures, clavicle fractures, shoulder

dislocationdislocation Other patterns: consider pathway of energy Other patterns: consider pathway of energy

exchangeexchange


Sports InjuriesSports Injuries



Sports injuriesSports injuries DecelerationDeceleration TorsionTorsion Exceeding range of motionExceeding range of motion ShearShear CompressionCompression



Sports injuriesSports injuries BoatingBoating ATVs, snowmobilesATVs, snowmobiles Contact sportsContact sports Skiing, skateboardingSkiing, skateboarding BicyclingBicycling Collision between participantsCollision between participants



Sports injuriesSports injuries What forces acted on the victim and how?What forces acted on the victim and how? Apparent injuries may indicate related, but Apparent injuries may indicate related, but

unapparent injuriesunapparent injuries What were points of contact and energy What were points of contact and energy

exchange?exchange? Protective equipment?Protective equipment? Damaged protective equipment?Damaged protective equipment? Reconstruct impact from eyewitnessReconstruct impact from eyewitness

accounts if possibleaccounts if possible


Blast InjuriesBlast Injuries



Blast injuriesBlast injuries WarfareWarfare TerrorismTerrorism IndustryIndustry

• MinesMines• Chemical plantsChemical plants• Fireworks plantsFireworks plants• FactoriesFactories• Grain elevatorsGrain elevators• TransportationTransportation

Gas leaksGas leaks



Click to play video



Blast injuriesBlast injuries Three initial phasesThree initial phases

• PrimaryPrimary

• SecondarySecondary

• TertiaryTertiary

Two subsequent phasesTwo subsequent phases• QuarternaryQuarternary

• QuinaryQuinary



Primary phasePrimary phase Pressure wave moves at up Pressure wave moves at up

to 10,000 ft/sec (3048 to 10,000 ft/sec (3048 m/sec)m/sec)• DismembermentDismemberment• Pulmonary contusionPulmonary contusion• PneumothoraxPneumothorax• Air emboliAir emboli• Tympanic ruptureTympanic rupture

Pulmonary manifestations Pulmonary manifestations may be immediate or may be immediate or delayeddelayed



Secondary phaseSecondary phase Fragmentation injuries Fragmentation injuries

(shrapnel)(shrapnel)• GlassGlass

• Auto partsAuto parts

• MetalMetal

• Building materialsBuilding materials



Tertiary phase (blunt Tertiary phase (blunt force injuries)force injuries) Contact with Contact with

ground/stationary objectground/stationary object Crushed by structural Crushed by structural

collapsecollapse Secondary and tertiary Secondary and tertiary

injuries are more injuries are more obvious, but primary obvious, but primary injuries can be more injuries can be more severesevere



Quarternary phaseQuarternary phase Heat and fumesHeat and fumes

Quinary (bomb-related injuries)Quinary (bomb-related injuries) Dirty bombs (bacteria, radiation, chemicals)Dirty bombs (bacteria, radiation, chemicals) Fragments of human (suicide bomber) remains Fragments of human (suicide bomber) remains

can be embedded in victimscan be embedded in victims


Regional Effects: Blunt TraumaRegional Effects: Blunt Trauma HeadHead

External injury should External injury should increase suspicion of increase suspicion of brain traumabrain trauma

Compression may lead Compression may lead to scalp to scalp laceration/hematoma laceration/hematoma and/or skull fractureand/or skull fracture

Shearing injuries result Shearing injuries result from continued forward from continued forward motion of the brain after motion of the brain after the skull comes to a the skull comes to a stopstop


Regional Effects: Blunt TraumaRegional Effects: Blunt Trauma

NeckNeck CompressionCompression

• Range of motion exceededRange of motion exceeded

• Axial loadingAxial loading

ShearShear• In a lateral impact to the torso, the torso accelerates In a lateral impact to the torso, the torso accelerates

away from the head, stretching the soft tissues and away from the head, stretching the soft tissues and vertebral column (distraction injury)vertebral column (distraction injury)



ThoraxThorax CompressionCompression

• May exceed tensile strength of ribsMay exceed tensile strength of ribs

• Pulmonary overpressure injuriesPulmonary overpressure injuries

• Compression of organsCompression of organs Pulmonary contusionPulmonary contusion Cardiac contusionCardiac contusion

ShearShear• Aortic transectionAortic transection

• Traumatic aortic aneurysmTraumatic aortic aneurysm



AbdomenAbdomen CompressionCompression

• Damage to solid organsDamage to solid organs

• OverpressureOverpressure Ruptured diaphragmRuptured diaphragm Hollow organsHollow organs Retrograde aortic flow ruptures aortic semilunar valveRetrograde aortic flow ruptures aortic semilunar valve

ShearingShearing• Occurs at points of attachment/fixation of organsOccurs at points of attachment/fixation of organs

Kidneys, liver, spleen, intestines, (full) bladderKidneys, liver, spleen, intestines, (full) bladder


Penetrating TraumaPenetrating Trauma

Same laws of physics and kinetic energy Same laws of physics and kinetic energy applyapply

The energy of a projectile is exchanged with The energy of a projectile is exchanged with individual tissue cellsindividual tissue cells Cells are crushed and destroyed, leaving a Cells are crushed and destroyed, leaving a

permanent cavitypermanent cavity Cells of elastic tissue accelerate away fromCells of elastic tissue accelerate away from

the impact leaving a temporary cavity that the impact leaving a temporary cavity that disappears when tissues rebounddisappears when tissues rebound



Larger projectile frontal area = more tissue Larger projectile frontal area = more tissue particles impacted = greater damageparticles impacted = greater damage ProfileProfile

• Initial size and change of size on impactInitial size and change of size on impact

TumbleTumble• Center of gravity of a projectile seeks to become the Center of gravity of a projectile seeks to become the

leading edgeleading edge

FragmentationFragmentation• More fragments create a greater total surface More fragments create a greater total surface

area and more tissue damagearea and more tissue damage



Weapon energyWeapon energy Low velocityLow velocity

• Usually causes injury Usually causes injury only with a sharp point only with a sharp point or edgeor edge

• Less secondary trauma Less secondary trauma (cavitation due to (cavitation due to dissipation of energy)dissipation of energy)

• Cone of injuryCone of injury


Penetrating TraumaPenetrating Trauma Weapon energyWeapon energy

Medium velocityMedium velocity• Most handguns and some riflesMost handguns and some rifles

High velocityHigh velocity• Hunting and assault riflesHunting and assault rifles• Creates a vacuum that pulls debris into its trackCreates a vacuum that pulls debris into its track





Weapon energyWeapon energy Consider the rangeConsider the range

• Air resistance (drag) slows velocityAir resistance (drag) slows velocity

• Greater distance = decreased velocityGreater distance = decreased velocity


Regional Effects: Penetrating TraumaRegional Effects: Penetrating Trauma

HeadHead Low velocity may not penetrate skullLow velocity may not penetrate skull Medium velocity missile may penetrate the skull, Medium velocity missile may penetrate the skull,

dissipating enough energy that it cannot exit, but dissipating enough energy that it cannot exit, but follows the curve of the skull or is deflected off itfollows the curve of the skull or is deflected off it

High velocity missiles transmit tremendous energy High velocity missiles transmit tremendous energy through the inelastic brain tissue, greatly through the inelastic brain tissue, greatly increasing intracranial pressure and may cause increasing intracranial pressure and may cause skull to “explode”skull to “explode”



ThoraxThorax Lung tissue is less dense, fewer tissue particles Lung tissue is less dense, fewer tissue particles

are impacted, less energy is transferred to the are impacted, less energy is transferred to the tissue, yet these injuries are still clinically tissue, yet these injuries are still clinically significantsignificant

Vascular systemVascular system• Pericardial tamponadePericardial tamponade

• ExsanguinationExsanguination

Esophageal perforation may not be detectedEsophageal perforation may not be detected

for several days but is a significant injuryfor several days but is a significant injury



AbdomenAbdomen Gas/liquid-filled structuresGas/liquid-filled structures Solid structuresSolid structures 30% of knife wounds require surgical intervention30% of knife wounds require surgical intervention 85% to 90% of medium-velocity wounds require 85% to 90% of medium-velocity wounds require

surgical interventionsurgical intervention



ExtremitiesExtremities Bone fragments become secondary projectilesBone fragments become secondary projectiles Stretch on muscles may tear blood vesselsStretch on muscles may tear blood vessels Adjacent blood vessels sustain intimal damage, Adjacent blood vessels sustain intimal damage,

leading to thrombosisleading to thrombosis


Using Kinematics in AssessmentUsing Kinematics in Assessment

With significant impact in blunt trauma, a With significant impact in blunt trauma, a bruise is not just a bruisebruise is not just a bruise Consider the compression and shearing forces Consider the compression and shearing forces

applied due to absorption of kinetic energyapplied due to absorption of kinetic energy The damage due to medium- and high-The damage due to medium- and high-

velocity missiles greatly exceeds the velocity missiles greatly exceeds the circumferencecircumference


SummarySummary

Kinematics predicts up to 90% of injuriesKinematics predicts up to 90% of injuries Knowledge of anatomy and energy exchange Knowledge of anatomy and energy exchange

is needed to understand kinematicsis needed to understand kinematics The same laws of physics apply to blunt and The same laws of physics apply to blunt and

penetrating traumapenetrating trauma Velocity is more important than mass in Velocity is more important than mass in

determining kinetic energydetermining kinetic energy


QUESTIONS?QUESTIONS?

Lesson 03

Education

rapid deceleration

general principles

kinematicsenergy

instructor

illustrative

particles

vehicle traveling

stopping time