Avascular necrosis results from either temporary or permanent loss of blood to the bones. Although it can happen in any bone, the condition tends to affect the ends of long bones, such as the femur. Causes include injury or long-term use of steroid medicines or alcohol. As the disease progresses, symptoms can include joint pain, limited range of movement, and osteoarthritis.
What Is Avascular Necrosis?Avascular necrosis is a disease resulting from the temporary or permanent loss of the blood supply to the bones. Without blood, the bone tissue dies and causes the bone to collapse. If the process involves the bones near a joint, it often leads to collapse of the joint surface.
Avascular necrosis is also known as:
- Aseptic necrosis
- Ischemic bone necrosis.
Understanding Bone RebuildingThe process of bone rebuilding takes place after an injury as well as during normal growth. Normally, bone continuously breaks down and rebuilds -- old bone is reabsorbed and replaced with new bone. The process keeps the skeleton strong and helps it to maintain a balance of minerals.
In the course of avascular necrosis, however, the healing process is usually ineffective and the bone tissues break down faster than the body can repair them. If left untreated, the condition progresses, the bone collapses, and the joint surface breaks down, leading to pain and arthritis.
What Bones Are Affected by Avascular Necrosis?Although it can happen in any bone, avascular necrosis most commonly affects the ends (epiphyses) of long bones such as the femur -- the bone extending from the knee joint to the hip joint. Other common sites of avascular necrosis include:
- Upper arm bone
The condition may affect just one bone, more than one bone at the same time, or more than one bone at different times.
Avascular necrosis usually affects men and women between 30 and 50 years of age. Depending on a person's risk factors and whether the underlying cause is trauma, it also can affect younger or older people. About 10,000 to 20,000 people develop avascular necrosis each year. Orthopedic doctors are the ones who usually diagnose the condition.