Dysbaric osteonecrosis and its radiographic classification in China.

Dysbaric osteonecrosis was found in 259 cases among 2260 examined hyperbaric workers from several occupations. No positive cases were found in the divers in shipyards and diving experiments. Naval divers showed the lowest incidence (2.1%) and fishery divers the highest (19.8%). Distribution of long bone lesions was 46.0% in upper humerus, 37.7% in upper femur, 8.3% in lower femur, and 8.0% in upper tibia. We classify long bone lesions into three radiographic stages, the first two on the basis of size of the bone lesions as projected on the radiographs, and the third stage on the basis of extension of the lesion toward articular destruction. The three-stage classification system correlates with the clinical symptoms, and the working capacity of the individual patients tends to correlate with the severity of dysbaric osteonecrosis and can be understood by the general public.