|
Bones are living tissue relying on blood vessels to bring blood to keep them alive. Most living tissues have blood vessels that come from many directions into the tissue. If one blood vessel is damaged, it may not cause problems. There may be a backup blood supply coming in from a different direction. Certain joints of the body have only a few blood vessels that bring in blood. When this blood supply is damaged, it usually results in what is called avascular bone necrosis. Avascular Necrosis of the Hip Causes
Many things can cause avascular necrosis. Anything that damages the blood supply to the hip can cause avascular necrosis. Injury to the hip itself can damage the blood vessels. Fractures of the femoral neck (the area connecting the ball of the hip joint) can damage the blood vessels. Hip dislocation can tear the blood vessels. It usually takes several months for avascular necrosis to show up. It can even show up and become a problem up to two years following this type of injury. Some medications are known to cause avascular necrosis. Cortisone is the most common drug known to lead to avascular necrosis. This is usually only a problem in patients who must take cortisone every day due to other disease processes, such as advanced arthritis, or to prevent rejection of an organ transplant. Avascular necrosis has not been proven to be caused by short courses of treatment with cortisone, such as one or two injections into joints to treat arthritis or bursitis. A clear link exists between avascular necrosis and alcoholism. Excessive alcohol intake somehow damages the blood vessels and leads to avascular necrosis. Deep sea divers and miners who work under great atmospheric pressures also are at risk for damage to the blood vessels. The pressure causes tiny bubbles to form in the blood stream, which can block the blood vessels to the hip, damaging the blood supply. Symptoms
The first symptom of avascular necrosis is pain when weight is placed on the hip. The pain can be felt in the groin area, the buttock area, and down the front of the thigh. As the problem progresses, the symptoms include development of a limp when walking and stiffness in the hip joint. Eventually, the pain will also be present at rest and may even interfere with sleep. Diagnosis
The diagnosis of avascular necrosis begins with a history and physical examination. Your doctor will want to know about your occupation, what other medical problems you have, and your medication use. You'll be asked whether you drink alcohol. A physical examination will be done to determine how much stiffness you have in the hip and whether you have a limp. Once this is done, X-rays or an MRI will most likely be ordered. Magnetic resonance imaging (MRI) is probably the most common test used to look for AVN of the hip. The MRI scan is very sensitive and can show even small areas of damage to the blood supply of the hip within hours after the damage has occurred. Treatment
Once avascular necrosis has occurred, treatment choices depend on how far along the problem is and your symptoms. While your symptoms may be reduced with pain medications and anti-inflammatory medications, no medical treatments will completely restore the blood supply to the femoral head and reverse the avascular necrosis. If the femoral head has not begun to collapse, your doctor may suggest an operation to try to increase the blood supply to the femoral head. When the femoral head has collapsed, the joint becomes painful and arthritic, and a hip replacemant arthroplasty is necessary.
|
