Avascular necrosis (osteonecrosis)

Avascular necrosis is the death of bone tissue due to a lack of blood supply. Also called osteonecrosis, it can lead to tiny breaks in the bone and cause the bone to collapse. The process usually takes months to years.

A broken bone or dislocated joint can stop the blood flow to a section of bone. Avascular necrosis is also associated with long-term use of high-dose steroid medications and too much alcohol.

Anyone can be affected. But the condition is most common in people between the ages of 30 and 50.

Some people have no symptoms in the early stages of avascular necrosis. As the condition worsens, affected joints might hurt only when putting weight on them. Eventually, you might feel the pain even when you're lying down.

Pain can be mild or severe. It usually develops gradually. Pain associated with avascular necrosis of the hip might center on the groin, thigh or buttock. Besides the hip, the shoulder, knee, hand and foot can be affected.

Some people develop avascular necrosis on both sides, such as in both hips or in both knees.

See your health care provider for ongoing pain in any joint. Seek immediate medical attention for a possible broken bone or dislocated joint.

Avascular necrosis occurs when blood flow to a bone is interrupted or reduced. Reduced blood supply can be caused by:

• Joint or bone trauma. An injury, such as a dislocated joint, might damage nearby blood vessels. Cancer treatments involving radiation also can weaken bone and harm blood vessels.
• Fatty deposits in blood vessels. The fat (lipids) can block small blood vessels. This can reduce blood flow to bones.
• Certain diseases. Medical conditions, such as sickle cell anemia and Gaucher's disease, also can lessen blood flow to bone.

Sometimes the cause of avascular necrosis not brought on by trauma isn't fully understood. Genetics combined with overuse of alcohol, certain medications and other diseases likely play a role.

Risk factors for developing avascular necrosis include:

• Trauma. Injuries, such as hip dislocation or fracture, can damage nearby blood vessels and reduce blood flow to bones.
• Steroid use. Use of high-dose corticosteroids, such as prednisone, is a common cause of avascular necrosis. The reason is unknown, but some experts believe that corticosteroids can increase lipid levels in the blood, reducing blood flow.
• Drinking too much alcohol. Having several alcoholic drinks a day for several years also can cause fatty deposits to form in blood vessels.
• Bisphosphonate use. Long-term use of medications to increase bone density might contribute to developing osteonecrosis of the jaw. This rare complication has occurred in some people treated with high doses of these medications for cancers, such as multiple myeloma and metastatic breast cancer.
• Certain medical treatments. Radiation therapy for cancer can weaken bone. Organ transplants, especially kidney transplants, also are associated with avascular necrosis.

Medical conditions associated with avascular necrosis include:

• Pancreatitis
• Gaucher's disease
• HIV/AIDS
• Systemic lupus erythematosus
• Sickle cell anemia
• Decompression sickness, also known as divers' disease or the bends
• Certain types of cancer, such as leukemia

Untreated, avascular necrosis worsens. Eventually, the bone can collapse. Avascular necrosis also causes bone to lose its smooth shape, possibly leading to severe arthritis.

To reduce the risk of avascular necrosis and improve general health:

• Limit alcohol. Heavy drinking is one of the top risk factors for developing avascular necrosis.
• Keep cholesterol levels low. Tiny bits of fat are the most common substance blocking blood supply to bones.
• Monitor steroid use. Make sure your health care provider knows about your past or present use of high-dose steroids. Steroid-related bone damage appears to worsen with repeated courses of high-dose steroids.
• Don't smoke. Smoking narrows blood vessels, which can reduce blood flow.

During a physical exam, a health care provider will press around your joints, checking for tenderness. They might also move the joints through different positions to see if the range of motion is lessened.

Imaging tests

Many conditions can cause joint pain. Imaging tests can help pinpoint the source of pain. Tests may include:

• X-rays. They can reveal bone changes that occur in the later stages of avascular necrosis. In the condition's early stages, X-rays usually don't show any problems.
• MRI and CT scan. These tests produce detailed images that can show early changes in bone that might indicate avascular necrosis.
• Bone scan. A small amount of radioactive material is injected into a vein. This tracer travels to the parts of bones that are injured or healing. It shows up as bright spots on the imaging plate.

The goal is to prevent further bone loss.

Medications

In the early stages of avascular necrosis, certain medications may help ease symptoms:

• Nonsteroidal anti-inflammatory drugs (NSAIDs). Over-the-counter medications like ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve) might help relieve pain associated with avascular necrosis. Stronger NSAIDs are available by prescription.
• Osteoporosis drugs. These types of medications might slow the progression of avascular necrosis, but the evidence is mixed.
• Cholesterol-lowering drugs. Reducing the amount of cholesterol and fat in the blood might help prevent the vessel blockages that can cause avascular necrosis.
• Medications that open blood vessels. Iloprost (Ventavis) might increase blood flow to the affected bone. More study is needed.
• Blood thinners. For clotting disorders, blood thinners, such as warfarin (Jantoven), might prevent clots in the vessels feeding the bones.

Therapy

Your health care provider might recommend:

• Rest. Restricting physical activity or using crutches for several months to keep weight off the joint might help slow the bone damage.
• Exercises. A physical therapist can teach exercises to help maintain or improve the range of motion in the joint.
• Electrical stimulation. Electrical currents might encourage the body to grow new bone to replace the damaged bone. Electrical stimulation can be used during surgery and applied directly to the damaged area. Or it can be administered through electrodes attached to the skin.

Surgical and other procedures

Because most people don't develop symptoms until avascular necrosis is advanced, your health care provider might recommend surgery. The options include:

• Core decompression. A surgeon removes part of the inner layer of bone. Besides reducing pain, the extra space inside the bone triggers the production of healthy bone tissue and new blood vessels.
• Bone transplant (graft). This procedure can help strengthen the area of bone affected by avascular necrosis. The graft is a section of healthy bone taken from another part of the body.
• Bone reshaping (osteotomy). A wedge of bone is removed above or below a weight-bearing joint, to help shift weight off the damaged bone. Bone reshaping might help postpone joint replacement.
• Joint replacement. If the affected bone has collapsed or other treatments aren't helping, surgery can replace the damaged parts of the joint with plastic or metal parts.
• Regenerative medicine treatment. Bone marrow aspirate and concentration is a newer procedure that might help avascular necrosis of the hip in early stages. During surgery, the surgeon removes a sample of dead hipbone and inserts stem cells taken from bone marrow in its place. This might allow new bone to grow. More study is needed.

Your health care provider might refer you to a doctor who specializes in disorders of the joints (rheumatologist) or to an orthopedic surgeon.

What you can do

Make a list of:

• Your symptoms, including those that seem unrelated to the reason you scheduled the appointment, and when they began
• Key medical information, including other conditions you have and history of injury to the painful joint
• All medications, vitamins or other supplements you take, including doses
• Questions to ask your provider

Ask a relative or friend to accompany you, if possible, to help you remember the information you receive.

Some questions to ask your provider about avascular necrosis include:

• What's the most likely cause of my symptoms?
• What tests do I need?
• What treatments are available?
• I have other health conditions. How can I best manage them together?

Don't hesitate to ask other questions.

What to expect from your doctor

Your provider is likely to ask you questions, including:

• Where's your pain?
• Does a particular joint position make the pain better or worse?
• Have you ever taken steroids such as prednisone?
• How much alcohol do you drink?