1. An Introduction to the Physics of Trauma
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 Newton’s First Law of Motion
Law of Conservation of Energy

5. Kinetic Energy Energy of motion K.E. = 1/2 mass x velocity2
Major factor = Velocity
“Speed Kills”

6. Newton’s 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

7. Law of Conservation of Energy
Energy cannot be created or destroyed
Only changed from one form to another

8. 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.

9. Types of Trauma
Penetrating
Blunt
Deceleration
Compression

10. Motor Vehicle Collisions
Five major types
Head-on
Rear-end
Lateral
Rotational
Roll-over

11. Motor Vehicle Collisions
In each collision, three impacts occur:
Vehicle
Occupants
Occupant organs

12. Head-on Collision Vehicle stops Occupants continue forward
Two pathways
Down and under
Up and over

13. 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)

14. Head-on Collision Down and under pathway
Upper body hits steering wheel
Broken ribs
Flail chest
Pulmonary/myocardial contusion
Ruptured liver/spleen

15. Head-on Collision Down and under pathway Paper bag pneumothorax
Aortic tear from deceleration
Head thrown forward
C-spine injury
Tracheal injury

16. 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

17. Head-on Collision Up and over pathway Head impacts windshield
Scalp lacerations
Skull fractures
Cerebral contusions/hemorrhages
C-spine fracture

18. 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

19. Lateral Collision Car appears to move from under patient
Patient moves toward point of impact

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

21. Lateral Collision Hip hits door C-spine injury Head injury
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

24. Restrained vs Unrestrained
Ejection
27% of motor vehicle collision deaths
1 in 13 suffers a spinal injury
Probability of death increases six-fold

25. Restrained with Improper Positioning
Seatbelts Above Iliac Crest
Compression injuries to abdominal organs
T12 - L2 compression fractures
Seatbelts Too Low
Hip dislocations

26. Restrained with Improper Positioning
Seatbelts Alone
Head, C-Spine, Maxillofacial injuries
Shoulder Straps Alone
Neck injuries
Decapitation

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

28. Pedestrians Child Faces oncoming vehicle Waddell’s Triad
Bumper Femur fracture
Hood Chest injuries
Ground Head injuries

29. Pedestrians Adult Turns from oncoming vehicle O’Donohue’s Triad
Bumper Tib-fib fracture Knee ligament tears
Hood Femur/pelvic fractures

30. Falls Critical Factors Height Surface
Increased height = Increased injury
Always note, report
Surface
Decreased stopping distance = Increased injury

31. Falls Assess body part the impacts first
Follow path of energy through body

32. Fall Onto Buttocks Pelvic fracture Coccygeal (tail bone) fracture
Lumbar compression fracture

33. Fall Onto Feet Don Juan Syndrome Bilateral heel fractures
Compression fractures of vertebrae
Bilateral Colles’ fractures

34. Stab Wounds Damage confined to wound track Gender of attacker
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

35. Stab Wounds Chest/abdomen overlap
Chest below 4th ICS = Abdomen until proven otherwise
Abdomen above iliac crests = Chest until proven otherwise

36. Small wounds do NOT mean small damage
Stab Wounds
Small wounds do NOT mean small damage

37. 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

38. Gunshot Wounds
Severity cannot be evaluated in the field or Emergency Department
Severity can only be evaluated in Operating Room

39. Conclusion Look at mechanisms of injury
The increased index of suspicion will lead to:
Fewer missed injuries
Increased patient survival