Avascular Necrosis (Osteonecrosis)

What is avascular necrosis?

Avascular necrosis happens when something blocks the flow of blood to your bone tissue. Your bones are constantly changing as your skeletal system makes new bone tissue to replace aging bone tissue that eventually breaks down and dies.

Think of this as a cycle — your body makes new tissue to replace the tissue that’s breaking down and dying. This pattern needs to happen correctly to keep your bones healthy and strong. Blood carries the nutrients and oxygen bones need to stay healthy and regenerate. Without blood flow, your skeletal system can't make new bone tissue fast enough. The dying bone begins to crumble and eventually collapses.

How common is avascular necrosis?

Between 10,000 and 20,000 Americans develop avascular necrosis every year. It can affect all ages and genders, but this condition happens most often to people in their 30s and 40s.

Where does avascular necrosis develop?

Avascular necrosis can affect bone tissue in any joint, but typically targets your hip. Other joints that can develop avascular necrosis include:

• Ankles.
• Jaw.
• Knees.
• Upper arm (humerus) and shoulders.

What causes avascular necrosis?

Bone fractures or disease that prevent blood flow to bone tissue causes avascular necrosis. About 20% of avascular necrosis cases happen without an obvious cause.

Known causes of avascular necrosis are:

• Traumatic avascular necrosis: This can happen after you break a bone or dislocate a joint.
• Nontraumatic avascular necrosis: This happens if you have an illness or medical condition that keeps blood from flowing to your bone tissue. Nontraumatic avascular necrosis often affects the same bones on both sides of the body. For example, if you have avascular necrosis in your right shoulder, you're likely to have it in your left shoulder.

What bone fractures cause traumatic avascular necrosis?

Avascular necrosis is more likely in some bone fractures than others. Common bone fractures that lead to traumatic avascular necrosis are:

• Hip fractures and dislocations: About 20% of people who dislocate their hips (the hip is no longer aligned in the joint as it normally would be) develop avascular necrosis.

What medical conditions or problems cause nontraumatic avascular necrosis?

There are several medical conditions or treatment that can lead to avascular necrosis:

• Osteoporosis. Elderly women (and some men) sometimes have spontaneous avascular necrosis of the knee (SPONK).
• Blood disorders, such as sickle cell anemia.
• Diabetes.
• Cancer treatments, such as radiation therapy.
• Decompression sickness in scuba divers.
• HIV.
• Lupus.
• Organ transplants.

What lifestyle activities increase the risk of developing avascular necrosis?

Some lifestyle activities that increase that risk are:

• Excessive use of alcohol.
• Smoking.
• Prolonged corticosteroids use (prednisone).

What are the symptoms of avascular necrosis?

It might be weeks or months before you notice symptoms that might indicate you have avascular necrosis. Here are some symptoms that appear over time that could be signs of avascular necrosis:

• Intermittent pain that appears and eases when you put pressure on your bone and then remove the pressure.
• Increasing pain and stiff joints.
• Limited range of motion.
• Limping if you have avascular necrosis in your hips or knees.
• Difficulty climbing stairs, standing or walking.

How is avascular necrosis diagnosed?

Your healthcare provider will assess your symptoms and perform a physical exam. You may get one or more of these tests:

• X-rays to detect fractures and signs of arthritis.
• Magnetic resonance imaging (MRI).

How do healthcare providers treat avascular necrosis?

Your treatment will depend on the amount of damage to your bones. Potential treatments you might have if your bone damage is limited to smaller bones that don't bear weight include:

• Cold packs.
• Heat treatment.
• Rest.
• Nonsteroidal anti-inflammatory drugs (NSAIDs).
• Physical therapy to ease joint tenderness and increase range of motion.
• Walking aids such as canes and crutches.

What is the treatment for more advanced forms of avascular necrosis?

In most cases, you'll need surgery to treat your avascular necrosis. Surgical options can include:

• Core decompression: Your surgeon drills small holes (cores) in your affected bone to improve blood flow to the affected bone. This procedure might be combined with injections or bone grafts to promote healing.
• Joint replacement: They replace your damaged joint with an artificial one. Hip replacements and knee replacements are 95% effective at relieving pain and restoring mobility in people with avascular necrosis.

How can I prevent avascular necrosis?

You might not be able to prevent avascular necrosis, but there are steps you can take to reduce your risk:

• Quit smoking.
• Cut back on your alcohol intake.
• Watch your cholesterol levels.
• If you take corticosteroids for a chronic medical condition, talk to your healthcare provider about reducing your dosage.

Is there a cure for avascular necrosis?

Treatment can slow the progress of avascular necrosis, but there is no cure. Most people who have avascular necrosis eventually have surgery, including joint replacement. People who have avascular necrosis can also develop severe osteoarthritis.

When should I call my healthcare provider?

Avascular necrosis is a progressive condition that gets worse over time. If you have avascular necrosis, you should monitor your symptoms, such as pain and mobility.

You should call your healthcare provider if you have:

• Pain that doesn't improve with rest or pain relievers.
• Pain that makes walking or movement difficult.
• Unexplained limping.

What questions should I ask my healthcare provider?

You might want to ask your healthcare provider these questions:

• Why did I get avascular necrosis?
• What is the best treatment for me?
• What are the treatment complications?
• What type of follow-up care do I need after treatment?

A note from Cleveland Clinic

Avascular necrosis is a painful condition that can significantly affect your quality of life. Talk to your healthcare provider if you have illnesses or take medications that increase the risk you will develop avascular necrosis. Your provider will explain symptoms that might be signs of avascular necrosis. Early diagnosis and treatment can delay the condition's progress.