Avascular Necrosis

Overview

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 the bone's eventual collapse.

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

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

Symptoms

Many people have no symptoms in the early stages of avascular necrosis. As the condition worsens, your affected joint might hurt only when you put weight on it. Eventually, you might feel the pain even when you're lying down.

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

Some people develop avascular necrosis on both sides (bilaterally) — such as in both hips or in both knees.

When to see a doctor

See your doctor if you have persistent pain in any joint. Seek immediate medical attention if you believe you have a broken bone or a dislocated joint.

Causes

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, reducing the blood flow that feeds bones.
• Certain diseases. Medical conditions, such as sickle cell anemia and Gaucher's disease, also can cause diminished blood flow to bone.
• For about 25 percent of people with avascular necrosis, the cause of interrupted blood flow is unknown.

Avascular Necrosis Diagnosis

Your doctor will start with a physical exam. They’ll press on your joints to check for tender spots. They’ll move your joints through a series of positions to check your range of motion. You might get one of these imaging tests to look for what’s causing your pain:

Bone scan. The doctor injects radioactive material into your vein. It travels to spots where bones are injured or healing and shows up on the image.

MRI and CT scan. These give your doctor detailed images showing early changes in bone that might be a sign of AVN.

X-rays. They’ll be normal for early stages of AVN but can show bone changes that appear later on.

Avascular Necrosis Treatment

Treatment goals for AVN are to improve the joint, stop the bone damage, and ease pain. The best treatment will depend on a number of things, like:

• Your age
• Stage of the disease
• Location and amount of bone damage
• Cause of AVN

If you catch avascular necrosis early, treatment may involve taking medications to relieve pain or limiting the use of the affected area. If your hip, knee, or ankle is affected, you may need crutches to take weight off the damaged joint. Your doctor may also recommend range-of-motion exercises to help keep the joint mobile.

1. Medications. If the doctor knows what’s causing your avascular necrosis, treatment will include efforts to manage it. This can include:
2. Blood thinners. You’ll get these if your AVN is caused by blood clots.
3. Nonsteroidal anti-inflammatory drugs (NSAIDs). These will help with pain.
4. Cholesterol drugs. They cut the amount of cholesterol and fat in your blood, which can help prevent the blockages that lead to AVN.
5. Surgery. While these nonsurgical treatments may slow down the avascular necrosis, most people with the condition eventually need surgery. Surgical options include:
6. Bone grafts. Removing healthy bone from one part of the body and using it to replace the damaged bone
7. Osteotomy. Cutting the bone and changing its alignment to relieve stress on the bone or joint
8. Total joint replacement. Removing the damaged joint and replacing it with a synthetic joint
9. Core decompression. Removing part of the inside of the bone to relieve pressure and allow new blood vessels to form
10. Vascularized bone graft. Using your own tissue to rebuild diseased or damaged hip joints. The surgeon first removes the bone with the poor blood supply from the hip, then replaces it with the blood-vessel-rich bone from another site, such as the fibula, the smaller bone in your lower leg.
11. Electrical stimulation. An electrical current could jump-start new bone growth. Your doctor might use it during surgery or give you a special gadget for it.
12. Caring for Avascular Necrosis at Home

You can do these things to help:

1. Rest. Stay off the joint. This can help slow damage. You might need to hold back on physical activity or use crutches for several months.
2. Exercise. A physical therapist can show you the right moves to get range of motion back in your joint.
3. Prevention
4. To lower your risk of AVN:
5. Cut back on alcohol. Heavy drinking is a leading risk factor for AVN.
6. Keep your cholesterol in check. Small bits of fat are the most common thing blocking blood supply to you bones.
7. Use steroids carefully. Your doctor should keep tabs on you while you’re taking these medications. Let them know if you’ve used them in the past. Taking them over and over again can worsen bone damage.
8. Don't smoke. It boosts your AVN risk.

Prognosis for Avascular Necrosis

More than half the people with this condition need surgery within 3 years of diagnosis. If a bone collapse in one of your joints, you’re more likely to have it happen in another.

Your outlook depends on several things:

• Disease stage at the time you were diagnosed
• If you have an underlying condition
• You’re less likely to do well if:
• You’re over 50.
• You’re at stage III or higher when you’re diagnosed.
• More than a third of the bone’s weight-bearing area is dead.
• The damage goes past the end of the bone.
• You have a long history of cortisone treatments.