Evolution of femoral head deformity during the healing phase of Legg-Calvé-Perthes disease.

Progressive changes in the roundness of the femoral head were noted during the healing phase of hips with Legg-Calvé-Perthes disease. Forty-nine of 136 hips studied became progressively rounder, and 15 hips became progressively flatter after onset of reossification of the femoral head. The femoral head was more likely to undergo progressive flattening in older patients, in those with more severe lateral pillar involvement, and in those with prolonged reossification. These changes occurred during a 3- to 4-year reossification period after cessation of treatment.