Prosthetic replacement in osteonecrosis of the hip.

The young patient with avascular necrosis of the hip presents one of the unsolved problems in orthopaedics today. Many of these patients are active and have expectations of continuing activities that may be far in excess of reality, considering the results achieved in these patients with replacement arthroplasty. In contrast to this group of patients, the patient with systemic disease has a built-in "brake" and appears to do well with conventional arthroplasty. New fixation techniques are yielding more promising results, and continued research into new modes of fixation such as porous ingrowth may well cast a new light on the problem. At this time, however, the clinician is called on to evaluate not only the disease process but the anticipated continuing activity of the patient. Thus there is no one procedure appropriate for this disease but rather several alternatives, each having its own indication at a specific stage in the disease process.