We evaluated the clinical and radiological results of acetabular reconstructions using an acetabular roof reinforcement ring (ARR).

From May 1993 to November 1999, 18 hips revised with ARR were evaluated. The mean age at operation was 53 years. The average follow-up period was 51 months (24-94 months). Acetabular defects were classified based on the AAOS classification system. There was one case of type IIA defect, six cases of type IIB defect, ten cases of type III defect and one case of type IV defect. All were treated with morselized allografts and autografts, and three were reconstructed with additional structural autografts.

The average Harris hip score improved from 54 preoperatively to 76 postoperatively, but five patients complained of intermittent hip pain. On the last follow-up radiographs, the bone grafts were united and remodeled in all cases, but only partial resorption was observed in two hips. We found evidence of osteolysis in four hips and observed cup migration in three hips. Three hips, in which Muller rings were used, were re-revised during the follow-up period.

Acetabular reconstruction using ARR led to good clinical and radiological results, but a relative high rate of rerevision was shown in the cases fitted with the Muller ring. Appropriate ARR should be used depending on the extent of the acetabular defect.