Osteonecrosis, also known as avascular necrosis, is a condition characterized by bone death due to inadequate blood supply. Lack of blood flow may occur when there is a fracture in the bone or a joint dislocation that may damage nearby blood vessels. Chronic use of high doses of steroid medications and heavy alcohol consumption are the two main risk factors of osteonecrosis. Initially, small breaks appear in the bone that may eventually collapse. Hip joint is most commonly affected; however the knee and shoulder may also be involved.
The exact cause of the osteonecrosis is unknown. However one of the theories suggests that a stress fracture or trauma results in altered blood supply to the bone. Another theory says that fluid buildup within the bone increases the pressure on the blood vessels resulting in decreased circulation. If the condition is not diagnosed and treated early, it can result in severe osteoarthritis. Certain conditions and treatments that are associated with osteonecrosis include obesity, sickle cell anemia, lupus, kidney transplants, and steroid therapy. Steroid-induced osteonecrosis affects multiple joints and can be seen in younger patient groups.
The symptoms appear all of a sudden if it's a result of an injury. In other situations, the pain and stiffness may gradually appear over a period of time. Typically, osteonecrosis causes pain and restricted range of motion in the joint affected. The pain worsens with activity and at night. Your doctor will diagnose the condition using imaging tests such as X-rays, MRI scan and bone scan that help rule out other causes of joint pain.
The treatment is aimed at preventing further loss of bone and it depends on the bone damage that has occurred already. Conservative treatment would reverse early stages of avascular necrosis whereas surgical treatment may be required in more advanced stages.
- Medications: Nonsteroidal anti-inflammatory drugs (NSAID'S) may be prescribed that help control your pain and swelling
- Rest: Restriction of physical activities and use of crutches to decrease weight bearing on your joints may be beneficial
- Exercises: Regular exercises that improve your range of motion may be done
- Electrical stimulation: Electric currents promote new bone growth. They can be applied directly to the area of damage or through electrodes fixed on skin. It helps replace the damaged bone
- Core decompression: During this procedure, a portion of the inner layer of the bone is removed to relieve the pressure inside the bone. This decreases the pain and allows growth of new blood vessels thereby stimulates new bone growth
- Bone transplant: A healthy bone from harvested from other part of your body is grafted into the affected area.
- Bone reshaping (osteotomy): This procedure is done in advanced stages and involves reshaping of the bone which is done to decrease the stress placed over the affected bone.
- Joint replacement: Joint replacement surgery is done as a last resort when the bone has collapsed needing artificial replacement