Lateral growth disturbance of the proximal femur may occur after treatment of developmental dysplasia of the hip, although usually it is not recognized until the child is older. This resultant dysplasia is also known as Kalamchi and MacEwen Type II avascular necrosis. The valgus configuration of the proximal femur and associated acetabular dysplasia may need operative reconstruction. Our purpose in doing this study was to assess the results of reconstruction in these patients. We reviewed 24 patients (30 hips) with Type II avascular necrosis who had acetabular and/or proximal femoral osteotomy after treatment for developmental dysplasia of the hip. The results were assessed according to the timing and type of operation and were graded using the Severin classification (I and II satisfactory and III and IV unsatisfactory). All patients were followed up past skeletal maturity. At a mean followup of 22 years, 15 of 24 patients (17 of 30 hips) had a satisfactory result. The patients with hips that were reconstructed after the diagnosis of Type II avascular necrosis had more satisfactory results than those operated on before the diagnosis of (70% versus 50%) avascular necrosis. Patients with 10 of the 13 hips that had acetabular and femoral reconstruction had a satisfactory result.