Injury that slows or stops blood flow to a bone is the main cause of AVN. Other common risks and causes of AVN are:
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:
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.
There are a great number of risk factors engendering avascular necrosis. These following risks are considered as the most common ones including:
Injuries, such as hip dislocation or fracture, can damage nearby blood vessels and reduce blood flow to bones.
High-dose use of corticosteroids, such as prednisone, is the most common cause of avascular necrosis that isn’t related to trauma. The exact reason is unknown, but one hypothesis is that corticosteroids can increase lipid levels in your blood, reducing blood flow and leading to avascular necrosis.
Excessive alcohol use
Consuming several alcoholic drinks a day for several years also can cause fatty deposits to form in your blood vessels.
Long-term use of medications to increase bone density may be a risk factor for developing osteonecrosis of the jaw. This complication has occurred in some people treated with these medications for cancers, such as multiple myeloma and metastatic breast cancer. The risk appears to be lower for women treated with bisphosphonates for osteoporosis.
Certain medical treatments
Radiation therapy for cancer can weaken bone. Organ transplantation, especially kidney transplant, also is associated with avascular necrosis.
Besides, some medical conditions related to avascular necrosis may include:
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:
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.
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:
Dentists often find AVN in the jaw by seeing exposed bone during a mouth exam.
Treatment for AVN depends on:
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:
AVN in the jaw
Most of the time, surgery isn’t needed for AVN in the jaw. Treatment may include:
AVN in a small area of bone
If your doctor found AVN early before much damage has occurred, your treatment may include:
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.
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.