What Is Avascular Necrosis?

Avascular necrosis (AVN) is a condition that happens when there is loss of blood to the bone. Because bone is living tissue that requires blood, an interruption to the blood supply causes bone to die. If not stopped, AVN can cause the bone to collapse.

It most often affects your hip. Other common sites are the shoulder, knees, and ankles.

Avascular necrosis is also called osteonecrosis, aseptic necrosis, and ischemic bone necrosis.

Symptoms of Avascular Necrosis

In its early stages, AVN typically causes no symptoms. As the disease gets worse, it becomes painful. At first, it might only hurt when you put pressure on the affected bone. Then, pain may become constant. If the bone and surrounding joint collapse, you may have severe pain that interferes with your ability to use your joint. The time between the first symptoms and bone collapse can range from several months to more than a year.

Causes of Avascular Necrosis

Causes of AVN include:

  • Dislocation or fracture of the thigh bone (femur). This type of injury can affect the blood supply to the bone, leading to trauma-related avascular necrosis. AVN may develop in 20% or more of people who dislocate a hip.
  • Chronic corticosteroid use. Long-term use of these inflammation-fighting drugs, either orally or intravenously, leads to 35% of all cases of nontraumatic AVN. Although the reason for this is not understood, doctors suspect these drugs may interfere with the body's ability to break down fatty substances.
  • Excessive alcohol use. Much like corticosteroids, excessive alcohol may cause fatty substances to build in the blood vessels and decrease the blood supply to the bones.
  • Blood clots , inflammation , and damage to the arteries . All of these can block blood flow to the bones.

Other conditions associated with nontraumatic AVN include:

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Who Gets Avascular Necrosis?

As many as 20,000 people develop AVN each year. Most are between ages 20 and 50. For healthy people, the risk of AVN is small. Most cases are the result of an underlying health problem or injury.

Treatment for Avascular Necrosis

The goals of treatment for AVN are to improve the joint, stop the bone damage, and reduce 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

Medical Treatment for Avascular Necrosis

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.

  • Medications. If the cause of your avascular necrosis is known, treatment will include efforts to manage it. This can include:
  • Surgery. While these nonsurgical treatments may slow down the avascular necrosis, most people with the condition eventually need surgery. Surgical options include:
    • Bone grafts. Removing healthy bone from one part of the body and using it to replace the damaged bone
    • Osteotomy. Cutting the bone and changing its alignment to relieve stress on the bone or joint
    • Total joint replacement. Removing the damaged joint and replacing it with a synthetic joint
    • Core decompression. Removing part of the inside of the bone to relieve pressure and allow new blood vessels to form
    • 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 and then replaces it with the blood-vessel-rich bone from another site, such as the fibula, the smaller bone in the lower leg.
    • 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.

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Home Treatments for Avascular Necrosis

You can do these things to help:

  • 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.
  • Exercise. A physical therapist can show you the right moves to get range of motion back in your joint.

Prognosis for Avascular Necrosis

More than half the people with this condition need surgery within 3 years of diagnosis. Having a bone collapse in one joint makes you more likely to have it in the other.

Your prognosis 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.
WebMD Medical Reference Reviewed by David Zelman, MD on May 08, 2019

Sources

SOURCES:

National Osteonecrosis Foundation: "Osteonecrosis."

MedlinePlus.gov: "Osteonecrosis."

Penn State Hershey Medical Center: "Avascular Necrosis."

DukeHealth.org: "Free Vascularized Fibular Graft."

Lupus Foundation of America: “How lupus affects the bones.”

Mayo Clinic: “Avascular necrosis.”

Medscape: “Avascular Necrosis Follow-up.”

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