New Way to Restore a Flattened Hip Ball

Osteonecrosis is the death of bone. Osteonecrosis can cause the hip to collapse. This condition affects the ball on top of the thighbone (femoral head) when the blood supply is cut off. Adults between the ages of 20 and 50 years are at risk for osteonecrosis if they abuse alcohol, take steroids over a long time, or have some kind of trauma to the hip.

Treatment with surgery for early disease is usually successful. The goal is to prevent collapse of the femoral head. If it collapses, treatment is much more difficult. Total hip replacement is the most common treatment for patients over 50 years with bone collapse due to osteonecrosis. For patients younger than 50 with mild to moderate disease, the goal is to restore the round ball of the femur and to save the joint surface. This must be done to prevent collapse and before arthritic changes occur.

Doctors at the University of North Carolina at Chapel Hill propose using open surgery to inject cement into the damaged femoral head. The idea is that the cement will harden and support the area so it won't collapse. In general, pain is relieved, and mobility improves. If collapse occurs the ball can still be replaced. The results of this proposed treatment are being studied.

In the first study of 22 hips, the long-term results are still unknown. Right after surgery everyone in the study had pain relief and improved motion. After one to three years, six patients ended up needing a hip replacement. Patients with more advanced disease had the worst results.

There are five stages of osteonecrosis from stage 0 (at risk but no signs of disease) to stage IV (bone death with arthritic changes). At stage III, an X-ray or CT scan will show partial flattening of the ball. The authors suggest that patients under 40 with stage III disease could benefit with the cement treatment. But more work is needed to find ways to treat advanced stages of osteonecrosis.



References: Mark L. Wood, MD, et al. Cementation for Femoral Head Osteonecrosis: A Preliminary Clinic Study. In Clinical Orthopaedics and Related Research. July 2003. Vol. 412. Pp. 94-102.