[Bernese periacetabular osteotomy for the treatment of the degenerative dysplasic hip]

Appropriate management of degenerative joint disease in patients with dysplasic hips is a controversial issue. Non-surgical treatment is generally insufficient to achieve good long-term results and, in young patients, indications for total hip replacement, arthrodesis, or salvage procedures (Chiari, bone block) are limited. The most physiological option is to re-orient the acetabulum to cover the femoral head with a sufficient amount of joint cartilage. Several types of redirection osteotomy have been described. In the present work, we assess the clinical and radiological outcome after Ganz periacetabular osteotomy in patients with dysplastic hips who developed degenerative joints. We searched for factors influencing outcome.

This retrospective analysis was conducted in 57 patients with hip dysplasia who had undergone 64 peri-acetabular osteotomies for joint degeneration. Mean age at surgery was 31 years. The preoperative diagnosis was primary osteochondritis of the hip in 9 patients. The Merle d'Aubigné scores and VCE, VCA, HTE angles on standard x-rays were obtained before surgery and at last follow-up. The Tönnis grade for the severity of the joint degeneration was determined. In 19 patients, inter-trochanteric femoral osteotomy was performed to improve joint congruency in addition to peri-acetabular osteotomy. Clinical and radiological results were assessed at a mean follow-up of 3.5 years (range 2-6 years). The effects of age, cause of dysplasia, surgical history of the hip, severity of joint degeneration, association with femoral osteotomy, and learning curve were studied. Complications were recorded.

On the average, the Merle d'Aubigné score improved from 13 points preoperatively to 16.5 points at last follow-up. Limping was observed for a longer period after surgery in patients who had an associated inter-trochanteric osteotomy. At last follow-up, the overall score was lower in grade 3 hips than in grade 1 and 2 hips. Serious complications were observed in the first 15 patients. There was no statistical relationship between age at surgery or surgical history of the hip and final outcome. Comparing the preoperative x-rays with those obtained at last follow-up demonstrated an improvement in the mean value for VCE (2 degrees preoperatively to 25 degrees at last follow-up), VCA (- 6 degrees to 39.5 degrees ), and HTE (25 degrees to 15 degrees ). Radiologically, the severity of joints degeneration was improved or remained unchanged in 83% of the hips (especially for grade 1 and 2 hips).

In our hands, peri-acetabular osteotomy has provided good results, especially in terms of improved function and control of joint degeneration. Although this procedure is basically indicated for young patients with hip dysplasia free of joint degeneration, it would also be a useful alternative for those who have developed only moderately extensive joint degeneration (Tönnis grades 1 and 2) and a moderately excentric femoral head. Success in these patients depends on surgical experience, correct indications, and careful attention to technical details. Nevertheless, complications are not exceptional and the learning curve may be long. In our series, the main factor predictive of outcome was the Tönnis grade of joint degeneration.