KINEMATICS

1
KINEMATICS

• An Introduction to the Physics of Trauma

2
Trauma Statistics

• 100,000 trauma deaths/year
• One-third are preventable
• Unnecessary deaths often caused by injuries
  missed because of low index of suspicion
• Raise index of suspicion by evaluating scene as
  well as patient

3
Kinematics

• Physics of Trauma
• Prediction of injuries based on forces, motion
  involved in injury event

4
Physical Principles

• Kinetic Energy
• Newtons First Law of Motion
• Law of Conservation of Energy

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Kinetic Energy

• Energy of motion
• K.E. 1/2 mass x velocity2
• Major factor Velocity
• Speed Kills

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Newtons First Law of Motion

• Body in motion stays in motion unless acted on by
  outside force
• Body at rest stays at rest unless acted on by
  outside force

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Law of Conservation of Energy

• Energy cannot be created or destroyed
• Only changed from one form to another

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Conclusions

• When moving body is acted on by an outside force
  and changes its motion,
• Kinetic energy must change to some other form of
  energy.
• If the moving body is a human and the energy
  transfer occurs too rapidly,
• Trauma results.

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Types of Trauma

• Penetrating
• Blunt
• Deceleration
• Compression

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Motor Vehicle Collisions

• Five major types
• Head-on
• Rear-end
• Lateral
• Rotational
• Roll-over

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Motor Vehicle Collisions

• In each collision, three impacts occur
• Vehicle
• Occupants
• Occupant organs

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Head-on Collision

• Vehicle stops
• Occupants continue forward
• Two pathways
• Down and under
• Up and over

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Head-on Collision

• Down and under pathway
• Knees impact dash, causing knee
  dislocation/patella fracture
• Force fractures femur, hip, posterior rim of
  acetabulum (hip socket)

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Head-on Collision

• Down and under pathway
• Upper body hits steering wheel
• Broken ribs
• Flail chest
• Pulmonary/myocardial contusion
• Ruptured liver/spleen

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Head-on Collision

• Down and under pathway
• Paper bag pneumothorax
• Aortic tear from deceleration
• Head thrown forward
• C-spine injury
• Tracheal injury

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Head-on Collision

• Up and over pathway
• Chest/abdomen hit steering wheel
• Rib fractures
• Flail chest
• Cardiac/pulmonary contusions
• Aortic tears
• Abdominal organ rupture
• Diaphragm rupture
• Liver/mesenteric lacerations

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Head-on Collision

• Up and over pathway
• Head impacts windshield
• Scalp lacerations
• Skull fractures
• Cerebral contusions/hemorrhages
• C-spine fracture

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Rear-end Collision

• Car (and everything touching it) moves forward
• Body moves, head does not, causing whiplash
• Vehicle may strike other object causing frontal
  impact
• Worst patients in vehicles with two impacts

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Lateral Collision

• Car appears to move from under patient
• Patient moves toward point of impact

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Lateral Collision

• Chest hits door
• Lateral rib fractures
• Lateral flail chest
• Pulmonary contusion
• Abdominal solid organ rupture
• Upper extremity fracture/dislocations
• Clavicle
• Shoulder
• Humerus

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Lateral Collision

• Hip hits door
• Head of femur driven through acetabulum
• Pelvic fractures
• C-spine injury
• Head injury

22
Rotational Collision

• Off-center impact
• Car rotates around impact point
• Patients thrown toward impact point
• Injuries combination of head-on, lateral
• Point of greatest damage Point of
  greatest deceleration Worst patients

23
Roll-Over

• Multiple impacts each time vehicle rolls
• Injuries unpredictable
• Assume presence of severe injury
• Justification for
• Transport to Level I or II Trauma Center
• Trauma team activation

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Restrained vs Unrestrained

• Ejection
• 27 of motor vehicle collision deaths
• 1 in 13 suffers a spinal injury
• Probability of death increases six-fold

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Restrained with Improper Positioning

• Seatbelts Above Iliac Crest
• Compression injuries to abdominal organs
• T12 - L2 compression fractures
• Seatbelts Too Low
• Hip dislocations

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Restrained with Improper Positioning

• Seatbelts Alone
• Head, C-Spine, Maxillofacial injuries
• Shoulder Straps Alone
• Neck injuries
• Decapitation

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What injury is likely to occur even if a patient
was properly restrained?
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Pedestrians

• Child
• Faces oncoming vehicle
• Waddells Triad
• Bumper Femur fracture
• Hood Chest injuries
• Ground Head injuries

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Pedestrians

• Adult
• Turns from oncoming vehicle
• ODonohues Triad
• Bumper Tib-fib fracture Knee
  ligament tears
• Hood Femur/pelvic fractures

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Falls

• Critical Factors
• Height
• Increased height Increased injury
• Always note, report
• Surface
• Decreased stopping distance Increased injury
• Always note, report

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Falls

• Assess body part the impacts first
• Follow path of energy through body

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Fall Onto Buttocks

• Pelvic fracture
• Coccygeal (tail bone) fracture
• Lumbar compression fracture

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Fall Onto Feet

• Don Juan Syndrome
• Bilateral heel fractures
• Compression fractures of vertebrae
• Bilateral Colles fractures

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Stab Wounds

• Damage confined to wound track
• Four-inch object can produce nine-inch track
• Gender of attacker
• Males stab up Females stab down
• Evaluate for multiple wounds
• Check back, flanks, buttocks

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Stab Wounds

• Chest/abdomen overlap
• Chest below 4th ICS Abdomen until proven
  otherwise
• Abdomen above iliac crests Chest until proven
  otherwise

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Stab Wounds

• Small wounds do NOT mean small damage

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Gunshot Wounds

• Damage CANNOT be determined by location of
  entrance/exit wounds
• Missiles tumble
• Secondary missiles from bone impacts
• Remote damage from
• Blast effect
• Cavitation

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Gunshot Wounds

• Severity cannot be evaluated in the field or
  Emergency Department
• Severity can only be evaluated in Operating Room

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Conclusion

• Look at mechanisms of injury
• The increased index of suspicion will lead to
• Fewer missed injuries
• Increased patient survival