Growth of the proximal femur after varus-derotation osteotomy in the treatment of congenital dislocation of the hip.

The growth of the upper end of the femur was studied in 50 children with congenital dislocation of the hip in whom a femoral osteotomy had been carried out. All children had unilateral dislocations and had been treated by a proximal femoral varus-derotation osteotomy after closed reduction, excision of the limbus, or open reduction. The average age at osteotomy was 2.3 years. The minimum follow-up was five years (average, 11.6 years). The neck-shaft angle, CE angle, shaft-epiphysis angle, neck-epiphysis angle, diameter of the femoral head, and widths of the femoral neck and shaft were measured on the anteroposterior radiographs. Although no cases of avascular necrosis of the capital epiphysis occurred, 21 children developed deformities of the femoral head, of whom eight showed an abnormal angulation of the capital-epiphyseal plate. The neck-epiphysis angle is described as an alternative to the shaft-epiphysis angle in assessing the orientation of the capital-epiphyseal plate. The best radiographic outcome was obtained when the neck-shaft angle measured 100 degrees to 110 degrees immediately after osteotomy.