Skeletal muscle affection with pressure waves caused by extremity impact with high velocity missile. Light and electron microscopy study on dogs

ABSTRACT

Seven healthy adult dogs were used in this study. One was used as a negative control. Three were subjected to high-velocity missile injury in their left hind limb and considered as test animals. The other three were subjected to low-velocity missile injury lacking high-pressure waves and considered as positive controls. Small specimens of skeletal muscle were taken from the diaphragm and the right fore limb [distant limb from the shot site] of all animals for light and electron microscopic examinations. Specimens of the high velocity injured animals showed abnormal changes on electron microscopic examination in some muscle fibers as widened spaces between myofibrils and myofilaments and oblique spaces accompanied by disruption of sarcomeres. Also, distortion and irregularity of Z lines, widening and breaking of sarcoplasmic reticulum and bursting of some mitochondria were detected. These findings with normal appearance on gross and light microscopic examination could be attributed to the compression effect of the pressure waves accompanying high velocity missile injury. The absence of changes in the positive control specimens on electron microscopic examination confirms the suggested role of pressure waves. The more changes detected in the diaphragm specimens in contrast to those seen in the right fore limb could also be correlated to the distance from the site of injury