[Chiari's osteotomy in the adult. Apropos of 70 cases]

Seventy Chiari osteotomies have been performed between 1975 and 1986. Fifty-three cases have been reviewed with a follow-up greater than a year and with a mean of four years and eight months. In half of the cases, the operation was done for very dysplastic hips, usually at an advanced stage of osteoarthritis (stage two in 37.5 per cent and stage three in 25 per cent). Post-operative complications were very rare except for two cases of non-union. The functional results were very satisfactory, with 83 per cent of very good and good results, especially in respect of relief of pain which was remarkable. These results were sustained in the long-term follow-up; 21 hips had a follow-up of 5 to 11 years, with a mean of 6.8 years. Only two hips needed a total hip arthroplasty. Radiologically, the osteotomy produced normal antero-posterior and lateral hip measurements in almost all the cases, largely due to a considerable medial displacement of more than 20 mm in 87 per cent of cases. There was improvement in the osteoarthritic changes in 74 per cent of cases. The factors which affected the outcome favourably were the degree of dysplasia, a round femoral head and a technically correct operation, with bone division close to the femoral head and a sufficiently upward slope to the osteotomy. An advanced osteoarthritis is not a contra-indication if it is due to a very marked acetabular dysplasia.