Avascular necrosis is the destruction of bone from a loss of blood supply. It is also known as osteonecrosis, aseptic necrosis or ischemic necrosis.

Bone is living tissue. Many areas of bone require oxygenated blood to remain healthy. If the blood supply is cut off, the bone cells start to die. Tiny cracks develop in the affected area of the bone. Eventually, the bone collapses. Initially, patients may not have any symptoms. But as more bone is destroyed, there may be pain, joint stiffness and limitations in movement.

According to the American Academy of Orthopaedic Surgeons, about 10,000 to 20,000 cases of avascular necrosis occur each year. Men are affected more often than women. Although it can occur at any age, avascular necrosis is most commonly seen in people 20 to 50. The hip is the most commonly affected joint. However, the condition is also seen in the upper arm bones, shoulders, knees and ankles.

Avascular necrosis can be caused by trauma or any other condition that causes a disruption of blood supply to the bone. Some risk factors include: long-term use of steroids, consumption of alcohol, radiation therapy directed in the area of a bone, chemotherapy, lupus, sickle cell disease, arthritis and osteoporosis. Avascular necrosis sometimes affects scuba divers who develop the "bends."

Treating Avascular Necrosis of the Hip

If avascular necrosis is detected in early stages, before there is significant damage to the bone, doctors may try some conservative measures to allow the area to heal and, hopefully, return a blood supply to the bone. Non-steroidal anti-inflammatory medications may be used to reduce pain. Underlying medical conditions need to be treated and controlled. Patients should stop smoking and avoid alcohol.

Doctors also will recommend taking the weight off the affected hip by using crutches or other types of mobility aids. Exercises may be needed to maintain or increase range of motion in the joint.

When conservative measures fail to reduce pain, surgery may be recommended. Dean Sotereanos, M.D., an Orthopaedic Surgeon at Allegheny General Hospital, is using a technique called a vascularized fibular graft. An incision is made into the hip to access the damaged joint. Then the diseased portion of the bone is removed. Another incision is made into the leg to access the fibula, the smaller of the two bones in the lower leg. A small portion of the fibula is removed along with a connecting artery and vein. Next, a hole is drilled into the top of the thigh bone. The donor section of the fibula is inserted in the hole. Then the artery and vein from the fibula are connected to the blood vessels in the hip. The goal of the surgery is to provide a new source of blood supply to the hip. Ideally, that will lead to the formation of new, healthy bone cells, reducing pain and restoring range of motion.

Patients are in the hospital for a few days after surgery and then sent home with crutches. It's important to keep weight off the affected side of the body for six to eight months to give time for the blood supply to take hold and allow the area to heal and build strong bone. Patients are advised to avoid sports activities for at least a year. It can take one to two years before doctors know whether the procedure has worked. If it is successful, it's usually a permanent fix for the problem.

Sotereanos says some patients with avascular necrosis undergo joint replacement surgery. However, this isn't always a good option for younger patients because they usually want to remain active. In addition, the artificial joints wear out, often within 10 years, requiring additional surgery to replace the prosthesis.

For information on avascular necrosis:

Arthritis Foundation

National Institute of Arthritis and Musculoskeletal and Skin Diseases