Avascular necrosis (osteonecrosis) is when the bone tissue dies due to a lack of blood supply. It can lead to tiny breaks in the bone and the bone's eventual collapse.
If the bone is fractured or the joint becomes dislocated, the blood flow to a section of the bone can be interrupted, thus not feeding the bone. Avascular necrosis is also associated with long-term use of high-dose steroid medications and excessive alcohol intake.
Anyone can be affected by avascular necrosis. However, it is most common in people between 30 and 60 years of age. Having in mind this relatively young age, avascular necrosis can have significant long-term consequences.
Many people have no symptoms in the early stages of avascular necrosis. As the condition deteriorates, the affected joint may hurt only when it is under weight. The joint may hurt even when lying down.
There may be mild or severe pain and it 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 in both hips or in both knees.
Avascular necrosis occurs when blood flow to a bone is interrupted or reduced. Reduced blood supply can be caused by:
- Joint or bone trauma,
- Fatty deposits in blood vessels,
- Some diseases,
However, for some people with avascular necrosis, the cause of interrupted blood flow is unknown.
Risk factors for developing avascular necrosis include:
- Steroid use,
- Excessive alcohol use,
- Bisphosphonate use,
- Certain medical treatments.
Medical conditions associated with avascular necrosis include:
- Gaucher's disease,
- Systemic lupus erythematosus,
- Sickle cell anemia.
If untreated, avascular necrosis deteriorates with time. Eventually the bone may become so weakened that it collapses and breaks. Avascular necrosis also causes the bone to lose its smooth shape, potentially leading to severe arthritis.
To reduce the risk of avascular necrosis and improve the general health, the person needs to:
- Limit alcohol. Heavy drinking is one of the top risk factors for developing avascular necrosis.
- Keep cholesterol levels low. Tiny bits of fat are the most common substance blocking blood supply to bones.
- Monitor steroid use. Inform the doctor about any past or present use of high-dose steroids. Steroid-related bone damage appears to worsen with repeated courses of high-dose steroids.