Prognosticating factors in acetabular development following reduction of developmental dysplasia of the hip.

A number of predictors that may influence acetabular development after reduction were studied in 75 hips with developmental dysplasia of the hip (DDH). Seventy-nine percent of the hips had satisfactory results of Severin group I or II, and 21% had unsatisfactory results. The best predictor of success in a unilateral case is the center-head distance discrepancy (CHDD) measurement at 1 year follow-up. Ninety-six percent of hips with a CHDD of < or = 6% had satisfactory results, whereas 78% with a CHDD > 6% had unsatisfactory results. This study also confirms that age at reduction and significant improvement in the acetabular index in the first year after reduction are important predictors.