Dysbaric osteonecrosis by X-ray and CT scan in Chinese divers.

OBJECTIVE To compare the results of X-ray and CT scan for dysbaric osteonecrosis in Chinese divers. METHODS Both shoulders, hips and knees of 66 asymptomatic divers with diving duration of more than one year were examined by X-ray and CT scan. RESULTS The most frequent locations of dysbaric osteonecrosis were the upper femurs, followed by the upper humerus, lower femurs and upper tibias, and the most frequent radiographic lesions were calcification spots and cystic changes. Of the lesions detected, 38% (27/71) and 42% (95/229) werejuxta-articular of the femoral and humeral heads by X-ray and CT respectively. The detection rates of dysbaric necrosis (juxta- and/or other lesions) of X-ray and CT scan were 42.4% (95% confidence interval: 30.5%-54.3%) and 81.8% (95% CI: 72.4%-91.2%) respectively (p<0.05). If CT scan was used as the gold standard, the sensitivity of X-ray was 100% and the specificity was 31.6%. CONCLUSION CT scan showed a higher detection rate of dysbaric necrosis than X-ray. We recommend that CT scan be used for early diagnosis of dysbaric osteonecrosis.