Hip Osteonecrosis Symptoms and Treatment

Hip osteonecrosis, also called avascular necrosis, is a problem with the blood supply to bone of the hip joint. This condition occurs when there is an interruption of the blood flow to the head of the femur (the ball, of the ball-and-socket hip joint). The lack of normal blood supply to the bone cells causes a decrease in the delivery of oxygen and nutrients to the bone, and the bone cells subsequently die. When the bone cells are damaged, the strength of the bone is greatly diminished, and the bone is susceptible to collapse.

Causes

No one knows exactly what causes hip osteonecrosis. When hip osteonecrosis occurs, the bone collapses and the joint surface, the cartilage, loses its support. Because the cartilage loses the support of the bone underneath, the joint surface is quickly worn away, and arthritis quickly progresses.

Most patients with hip osteonecrosis are associated with either alcoholism or steroid use. Other risk factors for developing hip osteonecrosis include sickle cell disease, trauma to the hip (dislocation or fracture), lupus, and some genetic disorders.

Symptoms

Hip osteonecrosis usually has few warning signs. Patients often complain of new-onset hip pain and difficulty walking. Common symptoms of hip osteonecrosis include:

• Aching pain in the groin
• Pain with movement of the hip
• Difficulty walking or limp

The two tests that are most helpful in diagnosing and treating hip osteonecrosis are X-rays and MRIs. The X-ray may be completely normal, or it may show severe damage to the hip joint. If the X-ray is normal, an MRI may be performed to look for early signs of hip osteonecrosis.

Early osteonecrosis of the hip may not show up on a routine X-ray, but should always show up on an MRI test. Later stages of osteonecrosis will easily show up on an X-ray, and MRIs are not necessary and are typically not helpful. Unfortunately, often by the time hip osteonecrosis is evident on X-ray, the only surgical treatments that may be available are replacement procedures.

Other conditions that can have similar symptoms include osteoarthritis of the hip, transient osteoporosis of the hip, and back problems.

Treatment

Treatment of hip osteonecrosis is difficult because the problem tends to progress quickly despite intervention. In the early stages of hip osteonecrosis, crutches and anti-inflammatory medications can be helpful.

Surgical options in the early stages of hip osteonecrosis include hip decompression and bone grafting. Hip decompression is done to relieve increased pressure within the femoral head that may be contributing to the lack of normal blood flow. A hip decompression is done with the patient asleep in the operating room. Small holes are drilled into the area of hip osteonecrosis to relieve the pressure within the femoral head.

A vascularized bone graft moves healthy bone from the lower leg (along with the blood vessels attached to the bone), and places this into the area of hip osteonecrosis. The goal of this surgery is to deliver normal blood flow to the affected hip. Surgeons have also experimented with other types of grafts (including cadaver bone and synthetic grafts) to stimulate the healing of the bone in the femoral head. These procedures are done only in the early stages of hip osteonecrosis; if the cartilage has already collapsed, these surgical procedures are likely to be ineffective.

A common surgical treatment of hip osteonecrosis is total hip replacement. If there is damage to the cartilage of the joint, then hip replacement is probably the best option. While hip replacement works well, the replacements will wear out over time. This presents a significant problem in young patients diagnosed with hip osteonecrosis. Another option for younger patients is called hip resurfacing surgery. This procedure is similar to a standard hip replacement but removes the less normal bone.