1. BALLISTICS IN PENETRATING TRAUMA
CDR JOHN WEI, USN MC MD
4th Medical Battallion, 4th MLG
BSRF-12

2. OBJECTIVES Types of penetrating trauma Commonly encountered injuries
Basic ballistics
Expected wounds, operative planning, and treatment

3. TYPES OF PENETRATING TRAUMA
GSW
Rifle
Pistol
Shot gun
Stab
Blast

4. MECHANISM OF INJURY
Body and tissue trauma associated with cause of wounding
~500,000 gsw/year in USA
Risk of death and functional deficit
Surgical planning and treatment of wound

5. DEFINITIONS Ballistics Internal ballistics External ballistics
The science of mechanics that deal with the flight, behavior, and effects of projectiles
Internal ballistics
The study of processes originally accelerating the projectile
External ballistics
The study of the projectile as it passes through space
Terminal ballistics
The study of the interaction of the projectile with its target

6. INTERNAL BALLISTICS

7. DEFINITIONS Muzzle velocity
Velocity of the round as it leaves the barrel end
Kinetic energy (J) = 1/2 mass(kg) x velocity(m/sec)2
- 1 ft-lb= J, 1 grain= grams
-High velocity (rifle) vs. Low velocity (pistol)
Permanent vs temporary cavity
Ballistic coefficient- friction/drag of air against projectile
-based on shape and weight of projectile
Caliber- bullet diameter in inches (ie .22, .45)
Gauge- diameter of shotgun barrel (ie 12 ga.)

8. WOUND BALLISTICS Ballistic wound research in gelatin forms
Yawing and cavitation do not cause as severe tissue trauma as fragmentation
Temporary stretch cavitation in which tissue is pushed by the shock wave following the projectile

9. GUN SHOT WOUNDS Type of weapon / bullet used Distance from weapon
Location and trajectory/path of injury
Permanent vs temporary cavity

10. ENERGY OF DIFFERENT CALIBER PROJECTILES
J (m = 36g, v = 350 m/sec)
J (m = 50g, v = 900 m/sec)
J (m =120g, v = 300 m/sec)
J (m=165g, v=850 m/sec)

11. PERMANENT AND TEMPORARY CAVITATION
Permanent: tissue crush and excavation
Temporary: blast effect due to tissue stretch

12. MAXIMAL TEMPORARY CAVITY DIAMETERS
(170J) cm
(325J) cm
(1550J) cm
7.62mm (3500J) cm

13. BALLISTIC GEL CAVITATION

14. BULLET TYPES Full metal jacket Lead Softpoint, semi jacketed
Hollow point, ballistic tips

15. BULLET FRAGMENTATION
Increased tissue destruction compared to temporary cavity
Hague convention of 1899
Restrictions on use of expanding/fragmenting bullets

16. COMMON BULLETS .22 caliber Hand pistol Cheap and readily available
Low energy, lead bullet
Tumble tissue kinetics

17. .22 BULLET WOUND

18. COMMON BULLETS
.38 caliber
Pistol
Low velocity

19. .38 BULLET WOUND

20. COMMON BULLETS 7.62 x 39 AK-47, military use High velocity
Increased injury and tissue damage

21. COMMON BULLETS 30-06 Rifle Common hunting round Old military use
Fragmenting bullets
Old military use

22. SHOTGUN
“bird shot”
Multiple low energy spreading pellets, short range effect
“buck shot”
Fewer larger pellets
Slug
Single projectile, longer effective range

23. SHOTGUN BALLISTICS

24. SHOTGUN WOUND

25. KNIFE TRAUMA
Types
Penetrating stabbing
Soft tissue slash and cutting

26. KNIFE TRAUMA Type and length of knife Identify all external injuries
Determine potential internal injuries
Patient stabilization and life support
Local wound exploration, x-ray imaging, operation if needed

27. IMPALEMENT INJURIES Physical exam of neurologic and vascular function
Radiologic studies to determine anatomic injuries and bony fractures
Removal of object in operating room and repair of damaged structures

28. EXPLOSIVE BLAST INJURIES
Primary
Blast wave effect
Secondary
shrapnel
Tertiary
fall or landing blunt injury
Other
Burn, inhalation, smoke

29. EXPLOSIVE BLAST INJURIES

30. EXPLOSIVE BLAST INJURIES
Dominant cause of mortality and injury in current military actions
Large amount of tissue damage from explosive blast
Penetrating wounds from metal shell fragments, stones, human bones, automotive parts

31. EXPLOSIVE BLAST INJURIES
Primary projectiles from original explosive device: mortar round, grenade, or improvised explosive device
Secondary missiles from environment
Penetrating wounds complicated by gross contamination and massive tissue injury
Ballistics and trajectories unpredictable

32. EXPLOSIVE BLAST INJURIES

33. CONCLUSIONS Knowledge of mechanisms of wounding
Ballistics and kinetics help to diagnose and plan treatment of injuries
Associated injuries or wounding patterns from known mechanism should be looked for