Osteonecrosis of the Hip
Osteonecrosis of the hip is a painful condition that occurs when the blood supply to the head of the femur (thighbone) is disrupted. Because bone cells need a steady supply of blood to stay healthy, osteonecrosis can ultimately lead to destruction of the hip joint and severe arthritis.
Osteonecrosis is also called avascular necrosis (AVN) or aseptic necrosis. Although it can occur in any bone, osteonecrosis most often affects the hip. More than 20,000 people each year enter hospitals for treatment of osteonecrosis of the hip. In many cases, both hips are affected by the disease.
Your hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone).
The surface of the ball and socket is covered with articular cartilage, a smooth, slippery substance that protects the bones and enables them to glide easily across each other.
Causes of osteonecrosis of the hip
Osteonecrosis of the hip develops when the blood supply to the femoral head is disrupted. Without adequate nourishment, the bone in the head of the femur dies and gradually collapses. As a result, the articular cartilage covering the hip bones also collapses, leading to disabling arthritis.
Osteonecrosis can affect anyone, but is more common in people between the ages of 40 and 65. Men develop osteonecrosis of the hip more often than women.
Symptoms of osteonecrosis of the hip
Osteonecrosis develops in stages. Hip pain is typically the first symptom. This may lead to a dull ache or throbbing pain in the groin or buttock area. As the disease progresses, it becomes more difficult to stand and put weight on the affected hip, and moving the hip joint is painful.
It may take from several months to over a year for the disease to progress. It is important to diagnose osteonecrosis early, because some studies show that early treatment is associated with better outcomes.
Treatment of osteonecrosis of the hip
Although nonsurgical treatment options — such as anti-inflammatory medications, activity changes, and using crutches — can help relieve pain and slow the progression of the disease, the most successful treatment options are surgical. Patients with osteonecrosis that is caught in the very early stages (before the femoral head collapses) are potential candidates for hip-preserving procedures.
Total Hip Replacement
In total hip replacement, both the head of the femur and the socket are replaced with an artificial device.
If osteonecrosis has advanced to the point where the femoral head has already collapsed, the most successful treatment is total hip replacement. In this procedure, your doctor removes the damaged bone and cartilage, then positions new metal or plastic joint surfaces to restore the function of your hip.
