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Aseptic bone necrosis in Japanese divers.

Medical examination was performed on the divers in Ohura for 7 years from 1969 to 1972. Aseptic bone necrosis was found in 268 of 450 divers (59.5%). Men with over 5 years of experience in diving were highly affected (more than 54.4%). These bone lesions were found most frequently in the proximal end of the femur and the humerus. There was a significantly higher incidence of bone lesions in the men who dived over 30 meters. In the group of men with one or more bone lesions, 73.1% were known to have been treated for bends. The bone, once exposed to a certain compression of air, would have a tendency to develop bone lesions even after cessation of diving. Type A2 (linear opacity) led to the structural failure of the joint surface of the femur and the humerus. Histopathological study was carried out on the sections of bone obtained from three autopsy cases and four operated cases. Formation of air bubbles in the bone marrow cavity seemed to be the most important as the cause for the occurrence of aseptic bone necrosis, and local circulatory disturbance might be the most responsible for the progression of the bone lesion.