Avascular Necrosis

Avascular necrosis (AVN) is when your bone starts to die because it isn’t getting enough blood flow. AVN most commonly happens in the hip but can also affect your knees and shoulders.

Over time, AVN weakens the bone and the joint, causing pain and making it harder to move your hip the way it should. Without treatment, the condition only gets worse.

Doctors often first try to slow the progression with nonsurgical treatments, but most people with AVN will need surgery.

At UPMC, our orthopaedic surgeons and sports medicine specialists have a lot of experience treating people with AVN.

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On this page

• What Is Avascular Necrosis? 
• What Are the Symptoms of Avascular Necrosis? 
• How Do You Diagnose Avascular Necrosis?
• How Do You Treat Avascular Necrosis?

What is Avascular Necrosis (AVN)?

AVN happens when a bone loses its blood supply. Without blood bringing essential nutrients, the tissue in the bone dies and, in time, the bone collapses.

Also called osteonecrosis of the hip, AVN can also happen in other joints, like knees or shoulders, but it usually affects the hip. When it does, doctors call this AVN of the femoral head.

Your femoral head is the “ball” of the ball-and-socket joint in your hip. The femur (thighbone) fits into the cup-shaped socket of your pelvis. Muscles, tendons, and ligaments hold the joint in place.

Without enough blood flowing to this joint, the bone dies and the joint weakens. This leads to bone necrosis or bone death.

How common is avascular necrosis?

Doctors in the U.S. treat more than 20,000 people for AVN every year. AVN causes about 10% of hip replacements.

AVN usually affects adults between the ages of 40 and 65. However, the group most likely to get AVN are men between ages 40 and 50 who do manual labor.

In general, AVN is more common in men than women. However, women who have lupus or other autoimmune disorders are also at risk.

What are the stages of AVN?

AVN has four stages:

• Stage 1. You can’t see any bone damage on x-rays yet, but you can see damage on an MRI.
• Stage 2. You can start to see the damage on an x-ray, but the femoral ball hasn’t collapsed yet.
• Stage 3. You can see signs of the femoral ball starting to collapse (called a crescent sign).
• Stage 4. You can now see the collapse on an x-ray, and you can also see signs of osteoarthritis (damage to the cartilage).

What causes AVN?

Doctors don’t always know what causes AVN. But there are some things we know can reduce the blood supply to a bone.

These include:

• Blood clots, fatty deposits in blood vessels, or damage to arteries.
• Excessive alcohol use.
• Health problems, like Crohn's disease, lupus, sickle cell disease, and thrombosis.
• Injury complications, such as a bone fracture or joint dislocation.
• Legg-Calve-Perthes disease (in children).
• Prolonged use of steroids, such as prednisone.
• Radiation from cancer treatments, which can weaken bones and blood vessels.

The reason AVN happens in the hip more than any other place is that long bones like your femur are more at risk.

What are AVN risk factors and complications?

If you know you’re at risk for AVN, you can seek treatment earlier and potentially avoid complications.

AVN risk factors

Anyone can get AVN, but some people are more at risk, including people who:

• Are male.
• Drink heavily.
• Have autoimmune conditions, such as lupus or gout.
• Have hyperlipidemia (very high cholesterol, usually linked to genetics).
• Have long-term use of steroids.
• Have sickle cell disease.
• Work on assembly lines (repetitive trauma can cause AVN).

AVN complications

Left untreated, AVN can cause the tissue in the hip joint to die and, eventually, the bone can collapse. If this happens, walking without pain is very difficult.

In some cases, drugs like corticosteroids can cause this condition to worsen. If you've taken corticosteroids for a while, talk to your doctor about switching to a different drug to lower your risk of AVN. 

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What Are the Signs and Symptoms of Avascular Necrosis?

In the early stages of this bone disorder, you may not display any symptoms.

But as AVN progresses, you may have:

• Mild to moderate hip or groin pain.
• Pain while walking or when moving the hip. You may also have pain that radiates down to the knee.
• Stiffness in the hip joint.
• Trouble putting weight on one leg, often causing you to limp.

At first, the pain may get better with rest. But, in the later stages of AVN, the pain can be more constant. 

When should I see a doctor about AVN symptoms?

If you suspect you have avascular necrosis, you should see a doctor right away. The sooner you start treatment, the more you may be able to slow down the symptoms.

You don’t need a referral to make an appointment with UPMC orthopaedic doctors.

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How Do You Diagnose Avascular Necrosis?

The earlier doctors diagnose and treat AVN, the better the chances of a good recovery.

Your doctor will:

• Ask about your medical history, including any injuries you’ve had and what you do for a living.
• Perform an exam.
• Have you move your hip in different ways to pinpoint your pain and range of motion. 

Test to diagnose avascular necrosis

To be able to see if there’s damage to the bone, the doctor may order imaging tests, such as:

• X-rays
• MRI
• Bone scan
• CT scan
• Bone biopsy

The results of these imaging tests help us confirm the diagnosis and determine what stage you’re in. AVN has four stages, from mild to severe. If we can catch AVN in an early stage, when the hip is still healthy, there’s more we can do.

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How Do You Treat Avascular Necrosis?

Ultimately, doctors can’t cure avascular necrosis without surgery. But not everyone needs surgery immediately after diagnosis.

The first goal of AVN treatment is to prevent more damage to the hip and give the bone a chance to heal.

With AVN treatment, we try to focus on:

• Targeting the cause of the AVN.
• Fixing the problem.
• Healing the joint.

Your treatment will depend on the stage of the disease, your age, and your overall health.

Nonsurgical ways to treat AVN

Your doctor will first try conservative treatment for AVN.

This may include:

• Doing physical therapy.
• Resting.
• Using crutches to limit how much weight you put on the hip joint.

Electrical stimulation, where electrical currents help your body produce new bone, is another nonsurgical AVN treatment option.

Your doctor may also prescribe drugs, depending on the cause of your AVN.

These can include:

• Blood thinners to prevent clots.
• Cholesterol-lowering medicines.
• NSAIDs for pain.

Surgery to treat AVN

Sooner or later, most people with AVN need surgery as the condition gets worse.

Surgical options for AVN include:

• Bone graft. This surgery uses healthy tissue from another part of your body to rebuild the damaged hipbone. The goal is to help regenerate healthy bone. Recovery usually takes a few months.
• Core decompression. This surgery is a good option for AVN that’s in the early stages, but not if the bone has collapsed. The surgeon drills a hole in the core of the affected bone, which relieves pressure and helps new blood vessels form. Recovery takes about three months.
• Hip replacement. If you're in the third or fourth stage of AVN, you’ll most likely need a hip replacement. This surgery replaces the damaged parts of your hip joint with metal or plastic parts.
• Osteotomy. This is a surgery to change the shape of the bone to help move your weight off the bone. It’s a good option when just a small area of bone is affected. Recovery takes anywhere from three to 12 months.

Can you recover from avascular necrosis?

You can recover from AVN, but only with surgery. Nonsurgical treatment can help manage symptoms for a while, but these treatments can't cure it.

It’s similar to having severe osteoarthritis in your knees. There are ways to improve the pain for a while, but eventually, most people need a joint replacement to be pain-free.

Talk to your doctor about which surgical option is right for you. They all have recovery times that range from several weeks to several months. To fully recover, you’ll also need to do physical therapy.

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