Pathogenesis and prevention of dysbaric osteonecrosis

Japanese diving fishermen are known to have a high prevalence of dysbaric osteonecrosis. Their typical dive practices are characterized by long exposure to high pressure and by repetitive diving. The etiology of dysbaric osteonecrosis still remains controversial. Because the development of dysbaric osteonecrosis may occur silently, the diver may be unaware of the actual ischemic event. Moreover, key etiologic evidence is often lost before the diver is examined. The early stage of dysbaric osteonecrosis was evaluated in four autopsy cases of divers who died of acute decompression sikness. Hypercoagulability of blood was present in these cases. Hypercoagulability of blood has also been observed in experimental rats after decompression. Dysbaric osteonecrosis has been experimentally induced in six sheep at the University of Wisconsin - Madison. These findings are reviewed by comparing dysbaric osteonecrosis in both divers and experimental animals. In conclusion, a bone compartment syndrome and hypercoagulability appear to be pathogenetic factors in dysbaric osteonecrosis.