The relationship between mechanisms of wounding and principles of treatment of missile wounds.

Determinants of the wounding effects of a metallic projectile include the velocity, mass, shape, and stability of the missile, and whether it tumbles, deforms, or fragments within the body. The velocity, mass, shape, and stability influence its capability to penetrate through the skin, and the other factors influence the depth and volume of the wound. The energy lost into the tissues (kinetic energy deposition) is a greater determinant of potential wound volume than is the striking velocity, even though, because K.E. = 1/2 MV2, the potential striking K.E. is more strongly influenced by velocity than mass. The actual size and shape of the wound is influenced by tumbling, deformation, and fragmentation of the projectile and by the characteristics of the tissues and organs contacted. The pulsating temporary cavitation resulting from the passage of a high-velocity projectile produces blunt trauma that extends beyond the tissue actually contacted by the missile. The pulsation of the temporary cavitation with resulting strong negative pressure components permits contamination of the entire wound track of a perforating wound, with entrance of external contaminants from both the exit and the entrance sites. The extent and type of treatment required is determined more by the tissues and organs injured than by the characteristics of the wounding agent. Although extremity wounds from high-velocity projectiles may heal uneventfully, surgical exploration is indicated whenever there is a possibility of subfascial penetration, and obviously devascularized tissue should be excised. In circumstances in which contaminated devascularized tissue cannot be excised promptly or adequately, prophylactic topical antibacterial therapy (such as mafenide aqueous spray, which can penetrate through devascularized tissue) may prevent otherwise lethal infection.