Outcome of rotational acetabular osteotomy for early hip osteoarthritis secondary to dysplasia related to femoral head shape - 49 hips followed for 10-17 years

Background Hip osteoarthritis in Japanese patients is in most cases secondary and purpose to congenital dislocation of the hip or acetabular dysplasia - often associated with a deformed femoral head. Thus, we examined the outcome of rotational acetabular osteotomy (RAO) procedures in patients with early-stage osteoarthritis secondary to developmental dysplasia of the hip, and its relationship to femoral head deformity. Patients and methods We retrospectively reviewed the outcome of RAO procedures in 49 hips of 48 patients (43 females). All patients had radiographic evidence of early-stage osteoarthritis. The mean age was 33 (13-54) years at surgery, and the mean duration of follow-up was 13 (10-17) years. The roundness index of the femoral head was measured on preoperative radiographs. Clinical follow-up was performed using the Merle d'Aubign and Postel system. Results The mean preoperative clinical score was 13 points; this had improved to 17 points at the most recent follow-up (p 0.001). Radiographically, this procedure gave adequate improvement of femoral head coverage. At follow-up, stage of osteoarthritis was unchanged in 38 hips and had progressed in 11 hips. 2 of the 11 hips with progression of the osteoarthritic stage had obvious technical failure and were excluded from subsequent comparisons. The mean preoperative round index of the femoral head was different for the 38 hips with no obvious progression than for the 9 hips that showed progression (55% and 68%, respectively; p 0.001). Interpretation Patients with a deformed femoral head may experience progression of osteoarthritis within 10 years of the RAO procedure, even in early-stage osteoarthritis.