Avascular necrosis also called Osteonecrosis refers to a condition which results from lack of blood supply to bone tissue leading to bone death. Blood flow to the bone may be adversely affected from damage to the blood vessels, blockage by air or fat embolism in the blood vessels or by inflammation of the walls of the blood vessels. Though it can affect any bone, the ends of the thighbone (femoral heads) and shoulder are most commonly involved. Avascular necrosis is most common in young men below 50 years of age.
Injury to the bone is the main cause of avascular necrosis. Other possible causes include use of corticosteroid medications, excessive consumption of alcohol, and excess pressure inside the bone. Certain types of medical treatment such as radiation therapy, chemotherapy and organ transplantation also increases the risk of developing avascular necrosis.
There will not be any symptoms in the initial stages of the disease but as it progresses, patients will complain of pain and stiffness in the affected joint. Pain may be mild but can become worse at night or following physical activity. Sometimes pain may be so severe that range of motion of the joint will be restricted. If left untreated, severe arthritis can occur.
Early diagnosis is as important as an effective treatment plan. Your doctor will perform a complete physical examination and take a medical history. Imaging studies such as X-rays, MRI scan, CT scan and bone scans may help in diagnosis and tracking of the progression of the condition. Bone scans involve making an image of the bone with a special camera after a radioactive dye is injected into the veins.
Your doctor will advise a suitable treatment plan for you based on your age, stage of the disease, and the extent of bone involvement. Treatment options begin with nonsurgical means to provide pain relief but eventually surgical treatment is usually needed to restore function.
Nonsurgical treatment involves the use of anti-inflammatory medications to relieve pain, blood thinning agents to reduce blood clots affecting blood flow, and cholesterol lowering agents to reduce fat deposition. Your doctor may advise to restrict your activities and use crutches to reduce weight bearing. A range- of –motion exercise program may also be recommended.
If a nonsurgical approach remains unsuccessful, surgical treatment may be recommended. There are several surgical treatment options which include:
- Core Decompression: During this surgical procedure, the inner core portion of the bone is removed. This will reduce pressure inside the bone and increase blood flow. This treatment is suitable when avascular necrosis is in the initial stages.
- Osteotomy: This procedure is done in the early stages of the disease and when only a small portion of bone is affected. It involves reshaping of the bone to decrease the stress placed over the affected bone.
- Bone grafting: This procedure involves transplantation of healthy bone, taken from elsewhere in the body or a donor, into the area where core decompression has been performed.
- Total Joint Replacement or Arthroplasty: This is considered as a last resort when the disease has progressed to an advanced stage. The diseased joint will be replaced using artificial components.
Avascular necrosis if diagnosed and treated promptly offers a favorable outcome. The amount of unaffected bone greatly influences the treatment options and outcome.