Late results of Chiari's pelvic osteotomy. A follow-up of 171 adult hips.

Between 1971 and 1985, 461 adult patients were treated by Chiari's pelvic osteotomy with medial displacement. Of these, 161 patients (171 hips) were followed up for an average of 9 years. The average age at operation was 29 years. We describe five groups of painful dysplastic hips in which the operation is indicated. Clinical evaluation by Colton's rating system gave 84% of excellent, good or fair results. Radiographs showed that the secondary osteoarthritic changes were arrested in 73%, improved in 11% and that there was deterioration in 16%. Pain was largely or completely relieved in 87%, the range of movement was maintained in 80% and the gait improved in 77% of our cases. The late results were better in younger patients. We conclude that improved biomechanical conditions are responsible for good congruency of the joint which is preserved for a long time.