Avascular necrosis (AVN) is a disease of the bone. Necrosis is a general term that means a cell has died. AVN is also called:
- aseptic necrosis
- ischemic bone necrosis
- bone infarction
AVN can lead to joint pain, especially the hip.
The damage to the bone occurs from lack of blood flow to bone cells. That often happens from an injury. It’s also commonly due to damage from drinking too much alcohol or taking corticosteroids to manage a chronic health problem.
Read on to learn more about this condition.
Symptoms of AVN
The hip bone is the most commonly affected joint with AVN. AVN also commonly affects the knee. Less often, AVN affects bones in these areas:
In its early stages, AVN may not cause symptoms. As blood cells die and the disease progresses, symptoms may occur in roughly this order:
- mild or severe pain in or around the affected joint
- groin pain that spreads down to the knee
- pain that occurs when putting weight on the hip or knee
- joint pain severe enough to limit movement
Pain may dramatically increase in intensity because of tiny breaks in the bone, called microfractures. These can cause the bone to collapse. Ultimately, the joint may break down and develop arthritis.
The time between the first symptoms and the inability to move a joint varies. In general, it ranges from a few months to more than a year. Symptoms may appear bilaterally, meaning on both sides of the body.
If AVN develops in the jaw, symptoms include exposed bone in the jaw bone with pain or pus, or both.
Causes and risk factors for the condition
Injury that slows or stops blood flow to a bone is the main cause of AVN. Other common risks and causes of AVN are:
- drinking too much alcohol
- taking high doses of corticosteroids for a long time, such as prednisone or cortisone, because they can increase fatty substances (lipids) in the blood, which can block arteries
- childhood diseases including Legg-Calve Perthes disease
It’s not always clear what causes the problem with blood flow to the bone. Sometimes AVN affects healthy people. It may come on spontaneously, seemingly without a cause. Spontaneous AVN in the knee, for instance, is called SPONK or SONC.
Some less common causes of AVN include:
- the bends, also called decompression sickness and caisson disease, a condition caused by the rapid release of nitrogen into the blood
- taking bisphosphates, such as zoledronate/zoledronic acid (Reclast, Zometa) or pamidronate to treat cancer in the bone (These drugs are associated with rare instances of AVN in the jaw.)
- chemotherapy or radiation
- high cholesterol, high triglycerides, or both
- Gaucher’s disease
- HIV infection
- organ transplants, especially a kidney transplant
- sickle cell anemia or other blood disorders
Men develop AVN more than women unless the cause is injury or lupus. It most often affects people ages 30 to 60. But people of any age can develop AVN.
How AVN is diagnosed
Your doctor may check you for AVN if you have bone pain that is limited (localized) to a small area. To get a look at your bones, your doctor may recommend one or more of these imaging tests:
- X-ray: X-ray images may look normal in early stages of AVN. If you have AVN, your doctor will likely use X-rays to keep track of its progression.
- MRI scan: This type of imaging can help your doctor identify AVN in very early stages and before you experience symptoms. They also can show how much of the bone is affected.
- CT scan: This gives a 3-D picture of bone but is less sensitive than an MRI scan.
- Bone scan, also called nuclear bone scan or bone scintigraphy: Your doctor may recommend a bone scan if your X-rays are normal and you don’t have risk factors. This test requires that you get an IV with a harmless radioactive substance before the scan. The substance lets the doctor see inside the bones. A single bone scan finds any bones affected by AVN.
- Functional bone tests: If your doctor still suspects you have AVN even though your X-rays, MRIs, and bone scans were all normal, you may have tests to measure the pressure inside the painful bone. These tests require surgery.
Dentists often find AVN in the jaw by seeing exposed bone during a mouth exam.
Treatment for AVN
Treatment for AVN depends on:
- your age
- the cause of AVN
- which bones are damaged
- how much damage there is
Treatment is usually ongoing and changes as the disease progresses — from nonsurgical care to ease pain in the short term, to surgical care for lasting improvement. The goals of treatment are to:
- treat the cause of AVN
- reduce pain
- help you use the affected joint
- stop further damage to the joint and prevent collapse
- keep your bone and joint
AVN in the jaw
Most of the time, surgery isn’t needed for AVN in the jaw. Treatment may include:
- removal of dead tissue, called debridement
- taking antibiotics
- using medicated mouthwash
AVN in a small area of bone
If your doctor found AVN early before much damage has occurred, your treatment may include:
- taking pain medicines, such as nonsteroidal anti-inflammatory drugs
- reducing the risk of microfractures by using crutches or limiting activities, like walking, that put pressure on the affected joint
- doing range-of-motion exercises to help you be able to keep using the affected joint
- taking cholesterol-lowering medicines to improve blood flow
Some studies show taking bisphosphonate medicines, such as risedronate (Actonel), alendronate (Binosto, Fosamax), and ibandronate, may help prevent bone collapse in the hip or knee, or even improve it. These drugs may also be used for the treatment of osteoporosis.
AVN that is worsening or not responding to treatment
If pain and use of your joint are getting worse, you may need surgery to ease pain, prevent the bones from collapsing, and preserve your joint. Your doctor may talk with you about one or more of the surgical options
In core decompression, a surgeon drills one or more holes to remove a core of bone from the affected joint. The goal is to ease pressure in the joint and to make channels for new blood vessels to improve blood flow.
If AVN is caught early enough, this surgery may be able to prevent bone collapse and arthritis. Core decompression sometimes allows you to avoid a hip replacement later.
While your bone heals and enriches its blood supply, you may need to use a walker or crutches. Recovery may take a few months, but many people who have this procedure have complete pain relief.
Bone grafting is often done along with core decompression. A surgeon takes a small piece of healthy bone from another part of your body and grafts (transplants) it to replace the dead bone. Alternatively, the surgeon may use a donor or synthetic bone graft. This surgery improves blood flow and helps support the joint.
If the surgeon also takes blood vessels with the bone piece, the procedure is called a vascular bone graft.
It can take several months to recover from a bone graft.
Vascularized fibula graft is a specific type of bone graft used for AVN in the hip. This surgery is more involved than some of the other options. A surgeon removes the small bone in your leg, called the fibula, as well as its artery and vein. The surgeon grafts this bone into the hole created by core decompression. Then the surgeon reattaches the blood vessels.
Osteotomy is another option. A surgeon removes dead bone and also repositions, or reshapes, the healthy bone that remains. This helps reduce stress on and improve support of the joint so you can use it better.
It can take several months of limited activities to recover from this surgery.
Bones have collapsed or are destroyed
To restore the use of your hip and ease pain, a surgeon can replace your hip with an artificial one. This surgery is called total hip replacement, or arthroplasty. Your doctor will talk with you about the best type of replacement for you. Hip replacement eases pain and returns full use of the joint in about 90 to 95 percent of the people who have it.
Outlook for this condition
Most people with AVN will eventually need surgery. With the right treatment, many people with AVN can lead an active life. It’s important to limit activities and follow your doctor’s advice to protect your joint. If you do develop osteoarthritis in the joint with AVN, you can work with a physical therapist to help ease pain and stiffness.
A lot of research is being done to improve AVN treatment.
How to prevent AVN
You may be able to prevent AVN by taking these actions:
- Avoid drinking too much alcohol.
- Avoid or quit smoking.
- If you need corticosteroids to manage a chronic illness, talk to your doctor about the smallest dose you can take for the shortest time.
To specifically prevent AVN in the jaw:
- Brush your teeth and see your dentist for regular cleaning and screenings.
- See your dentist right away for jaw pain or gum problems, including swelling or redness. These can be signs of infection.
- If you need bisphosphonate treatment, have any dental work you need first. Also, be sure to take good care of your teeth while you take bisphosphonates.