Acetabular remodelling in Perthes' disease after primary healing.

We conducted a study to assess the remodelling potential of the acetabulum of 29 children with Perthes' disease. In all but four, the acetabular head index (AHI) increased in the time between primary healing of the femoral head and follow-up at skeletal maturity. We classified 13 cases (44.8%) in which the increase in AHI was more than 10% as group I. In this group, the outcome at follow-up was predictable when subluxation during the active phase of the disease decreased until primary healing. Our observations suggest that the position of the femoral head, rather than sphericity, is the most important factor in acetabular growth and remodelling.