Acetabular development in congenital dislocation on the hip.

Acetabular dysplasia is one of the most common complications in the treatment of congenital dislocation of the hip (CDH). Acetabular development is analyzed in a series of 47 children with 55 CDH with delayed diagnosis. Cases were studied on an overall basis and according to the type of reduction realized: closed (group 1) or open (group 2). The incidence of acetabular dysplasia in relation with the development of avascular necrosis (AN) of the hip during treatment was studied. Cases with an acetabular index (AI) of greater than 25 degrees two or more years after reduction were considered suggestive of dysplasia. Acetabular development was better in CDH treated by open reduction. Acetabular remodeling in dislocated hips treated by reduction and affected by AN was less than in reduced CDH free of AN. AI improves progressively during treatment of CDH, more markedly in the first post-reduction year.