We studied the natural history of nontraumatic avascular necrosis of the femoral head (ANFH) in 115 hips in 87 patients, 69 steroid-induced, 21 related to misuse of alcohol and 25 idiopathic. The average length of follow-up was over five years. Collapse occurred most often when the focus of bone necrosis occupied the weight-bearing surface of the femoral head. Flatness of the head due to subchondral fracture was an early manifestation of collapse. Classification into six types based upon the radiographic findings provided an accurate prognosis for individual cases of ANFH which is useful in planning treatment and in assessing its outcome.

We assessed the results of Chiari pelvic osteotomy in 64 hips with early osteoarthritis in terms of acetabular labral detachment detected pre-operatively by arthrography. At an average follow-up of four years, assessment by the Merle d'Aubigne score showed 83% excellent or good results. These satisfactory results were achieved in only half the cases with a detached labrum, but in nearly all cases with normal or torn acetabular labra. Other factors such as the acetabular index, the level and angle of osteotomy, and the displacement following osteotomy did not affect the results. Chiari pelvic osteotomy is a worthwhile procedure for early osteoarthritis in selected cases, but a detached acetabular labrum increases the risk of clinical failure.