[Risk factors of osteonecrosis of the femoral head following slipped capital femoral epiphysis].

UNLABELLED: Osteonecrosis is a serious complication of the treatment of slipped capital femoral epiphysis. The purpose of this study was to identify factors predisposing to the development of this complication. We reviewed retrospectively 127 patients (150 hips) treated for slipped capital femoral epiphysis in our institution between 1980 and 2004. Clinical and radiological data were analyzed before and after treatment, and at consecutive follow-up examination. Osteonecrosis was defined in the basis of radiological criteria. The risk of development of osteonecrosis was correlated with multiple clinical and radiographic parameters.

RESULTS: 12 hips in 11 patients (8%) had development of osteonecrosis. Ten of them had an unstable slip. From 130 stable hips, regardless of grade, two had development of osteonecrosis. In patients who had presented with an unstable hip, the risk of osteonecrosis increased with the grade of the slip. Osteonecrosis was more likely to develop in hips that had been treated with multiple screws than in those who had been treated with a single screw. In conclusion, partial or complete reduction of an unstable slipped capital femoral epiphysis increases the risk of development of osteonecrosis. Pinning in situ without reduction with a single screw is the method of choice of the treatment of a slipped capital femoral epiphysis.