Which of the following statement(s) is/are true concerning the biomechanics of penetrating injuries?

b. A hollow point bullet is associated with an enlarged area of injury

c. A high velocity gunshot wound creates a vacuum pulling clothing, bacteria, and other debris into the wound

Penetrating trauma involves the transfer of energy to a relative small tissue area. The kinetic energy of a bullet disrupts and fragments cells and tissues, moving them away from the path of the bullet. The actual size of the frontal area of impact is determined by three factors—profile, tumble (spin and yaw), and fragmentation. A knife or jacketed bullet does not deform significantly during impact, whereas a hollow-point bullet flattens, spreads, and fragments on impact and therefore enlarges the area of injury. Low energy missiles including knives and other objects produce damage only by sharp cutting edges. Cavitation is minimal, and injury can be predicted simply by tracing the pathway of the weapon within the body. Low, medium and high velocity gunshot wounds, however, produce damage not only to tissue directly in the path of the missile but also produce cavitation injury to tissues in close proximity to the impact. The size of the cavitation injury is directly proportional to the bullet’s velocity. The essential difference between high velocity weapons and low and medium velocity weapons is that the higher velocity weapons have a much larger cavity or pressure cone than low-and medium-velocity missiles. The temporary cavity extends well beyond the actual bullet tract, producing a wider injury. The vacuum created by the cavitation pulls clothing, bacteria, and other debris from the surrounding areas into the wound, creating the additional risk of contamination.