Small fragment wounds: biophysics and pathophysiology

This paper considers the wounding effects of small fragments in modern warfare. Small fragment wounds may be expected to predominate on a future conventional battlefield; however, studies and models of "military" wounds have tended to focus on bullets as the wounding projectile. This paper discusses briefly the types of fragment projectile expected from modern munitions. It goes on to define a model for such projectiles, and describes the interaction with soft tissue simulants. The extent of penetration, temporary cavitation, and contamination by foreign material are all considered. This work with simulants is validated by experimental shots against animal tissue. A wound model in an experimental animal is described. This model was used to investigate the hematologic, biochemical, and histologic effects of a small fragment wound. The effects on skin and skeletal muscle are described. By sampling at various times (up to 1 week) after wounding, the natural progress of these wounds has been ascertained. The results from 28 experimental animals, with untreated fragment wounds, are reported. The most important findings are that the skin damage is very localized and that the muscle damage is limited, with little necrotic tissue in the track. Furthermore, the extent of the muscle damage, peripheral to the wound track, improves with time, healing within a few days, provided the wound remains free from infection. There was no clinical or microbiologic evidence of infection in those animals followed for up to 3 days. However, of eight animals followed to 1 week, three developed infected wounds. This work has implications for the management of soft tissue wounds caused by fragmentation munitions. The conventional military approach has been to treat penetrating war wounds by exploration, debridement, excision of dead tissue, and delayed primary closure; conservative treatment has largely been regarded as inappropriate. The work presented here shows that the potential culture medium within the wound is small and can be removed by the normal bodily responses. There is no need for surgery, provided that infection can be prevented. It may be inferred that if bacterial colonization can be prevented in the early stages by the timely use of antibiotics, surgery may be unnecessary. Further studies are planned to investigate this possibility.