Avascular necrosis (AVN), also called osteonecrosis, aseptic necrosis, or ischemic bone necrosis, is a condition that occurs 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, this process eventually causes the bone to collapse.
Avascular necrosis most commonly occurs in the hip. Other common sites are the shoulder, knees and ankles.
Who Gets Avascular Necrosis and What Causes It?
1.¨Dislocation or fracture of the thigh bone (femur)
2.¨Chronic corticosteroid use
3.¨Excessive alcohol use
4.¨Fatty deposits in blood vessels
5.¨Certain diseases. Medical conditions, such as sickle cell anemia and Gaucher’s disease, Pancreatitis, Diabetes, HIV/AIDS
6.¨Certain medical treatments
7.¨Autoimmune diseases also can cause diminished blood flow to bone.
¨Decompression sickness, a condition that occurs when the body is subjected to a sudden reduction in surrounding pressure, causing the formation of gas bubbles in the blood
¨For about 25 percent of people with avascular necrosis, the cause of interrupted blood flow is unknown.
Symptoms of Avascular Necrosis
¨Many people have no symptoms in the early stages of avascular necrosis. As the condition worsens, your affected joint may hurt only when you put weight on it. Eventually, the joint may hurt even when you’re lying down.
¨Pain can be mild or severe and usually develops gradually. Pain associated with avascular necrosis of the hip may be focused in the groin, thigh or buttock. In addition to the hip, the areas likely to be affected are the shoulder, knee, hand and foot.
¨Some people develop avascular necrosis bilaterally — for example, in both hips or in both knees.
¨Untreated, avascular necrosis worsens with time. Eventually the bone may become so weakened that it collapses. Avascular necrosis also causes bone to lose its smooth shape, potentially leading to severe arthritis.
Tests and diagnosis
¨MRI and CT scan
¨Nonsteroidal anti-inflammatory drugs
¨Total joint replacement
Vascularized bone graft
¨ Joint mobilization
¨You may work with a physical therapist who will show you ways to safely move and stretch your hip. The goal is to keep your hip mobile and to avoid losing range of motion. Your therapist will also instruct you to use a walker or crutches.Keeping weight off your hip while you are standing or walking may help the bone to heal while protecting the femur from further damage.
After Surgery Physical Therapy Rehabilitation
¨After a simple drilling operation, you will probably use crutches for six weeks or so. The drill holes weaken the bone around the hip, making it possible to fracture the hip. Using crutches allows the bone to heal safely and reduce the risk that you may fracture your hip. Patients who have had bone and blood vessels grafted are required to limit how much weight they place on the hip for up to six months
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