Patients with acetabular dysplasia commonly undergo peri-acetabular osteotomy after skeletal maturity to reduce the risk of the late development of osteoarthritis. Several studies have suggested that deformity of the femoral head influences the long-term outcome. We radiologically examined 224 hips in 112 patients with acetabular dysplasia and early-stage osteoarthritis. There were 103 women and nine men with a mean age of 37.6 years (18 to 49). A total of 201 hips were placed in the acetabular dysplasia group and 23 in a normal group. The centre–edge angle and acetabular head index were significantly smaller (both p < 0.001), and the acetabular angle, acetabular roof angle and roundness index were significantly greater in the acetabular dysplasia group than those in the normal group (all p < 0.001). There were significant correlations between the roundness index and other parameters. Femoral head shape may be influenced by the severity of the acetabular dysplasia.

Cite this article: Bone Joint J 2013;95-B:1192–6.

Background: Deformity of the femoral head after open reduction for developmental dislocation of the hip (DDH) influences the outcome of pelvic osteotomy as a final correction for residual dysplasia to prevent secondary osteoarthritis. The purpose of this study was to review long-term outcomes after open reduction using a medial approach for DDH. The correlation between age at the time of operation and femoral head deformity at skeletal maturity was specifically evaluated.

Methods: Forty-two hips in 40 patients with more than 10 years of follow-up were assessed radiologically. The mean age at the time of surgery was 14.3 (range, 6–31) months, and the postoperative follow-up period ranged from 10 to 27 (mean, 15.8) years. The round and enlargement indices of the femoral head were measured on follow-up radiographs to evaluate deformity and enlargement of the femoral head at skeletal maturity.

Results: Severin classification was I and II in 16 hips; III, IV, and V in 23; and II at the final follow-up in the 3 hips treated by osteotomy less than 10 years after open reduction. Mean round index at follow-up was 58.3 ± 8.3 (range, 47–79); it showed correlation with age at the time of operation (r = 0.68, p < 0.001). Mean enlargement index at follow-up was 113.4 ± 11.8 (range, 93–137) and showed no correlation with age at the time of operation (r = 0.009, p = 0.96).

Conclusions: At more than 10 years’ follow-up, the occurrence of deformity of the femoral head correlated with increased age at the time of operation. Indications for use of a medial approach in the correction of DDH in older patients must take into account the risk of subsequent femoral head deformity at skeletal maturity.

We evaluated the results of rotational acetabular osteotomy in 44 hips (42 patients) with advanced osteoarthritis secondary to developmental dysplasia. The mean age of the patients at surgery was 43.4 years (30 to 59) and the mean follow-up was 12.1 years (8 to 19).

The mean Merle d’Aubigné clinical score improved from 10.8 points (8 to 15) pre-operatively to 13.5 points (6 to 18) at follow-up. Radiologically, this procedure produced adequate improvement regarding cover of the femoral head. At follow-up, the osteoarthritic stage assessed using the Japanese Orthopaedic Association grading, was improved in 11 hips (25%), unchanged in 22 (50%) and had progressed in 11 (25%). The mean pre-operative roundness index of the femoral head was significantly different in the 33 hips which had improved or maintained their osteoarthritic stage compared with the 11 which had progressed (53.7% vs 63.7%; p < 0.001).

Osteoarthritis with a round femoral head is considered to be an indication for rotational acetabular osteotomy, even in advanced stages of the disease.