Behavior of the proximal femur during the treatment of congenital dysplasia of the hip: a clinical long-term study.

The influence of the acetabular cover on the development of the proximal femur during the treatment of congenital dysplasia of the hip was studied in 47 children (58 hips) with a follow-up of 22 years. Varus osteotomy failed to correct hip dysplasia in 33 hips of 27 children. Chiari osteotomy was followed by a positive anti-Chiari effect (oval shaped acetabulum with proximal migration of the femoral head) in 15 children (20 hips). In five children (five hips) with coxa vara due to avascular necrosis, the anti-Chiari effect was negative. The combination of Chiari and varus osteotomy before the age of 8 years was followed by a positive anti-Chiari effect and recurrence of valgus deformity in seven of eight hips. The long-term failure of the varus and Chiari osteotomy, together with a review of clinical and experimental surveys, led us to prefer the acetabular redirectional osteotomy.