Avascular necrosis (also called osteonecrosis, aseptic necrosis, or ischemic bone necrosis) is a disease that results from the temporary or permanent loss of blood supply to the bone. When blood supply is cut off, the bone tissue dies and the bone collapses. If avascular necrosis occurs near a joint, collapse of the joint surface may occur.
Avascular necrosis may occur in any bone, but most commonly occurs in the ends of a long bone. It may affect one bone, several bones at one time, or different bones at different times.
Avascular necrosis may be the result of the following:
- traumatic causes (including injury, fracture, or damage to blood vessels)
- non-traumatic causes (including long-term use of medications, such as corticosteroids, or excessive, long-term use of alcohol)
Other theories and associations have been suggested as risk factors.
A risk factor is anything that may increase a person's chance of developing a disease. It may be an activity, such as smoking, diet, family history, or many other things. Different diseases have different risk factors.
Although these factors can increase a person's risk, they do not necessarily cause the disease. Some people with one or more risk factors never develop a disease, while others develop the disease and have no known risk factors.
But, knowing your risk factors to any disease can help to guide you into the appropriate actions, including changing behaviors and being clinically monitored for the disease.
Suggested risk factors for avascular necrosis include the following:
- steroid use
- Gaucher disease
- alcohol use
- blood disorders, such as sickle cell anemia
- radiation treatments
- decompression disease
The following are the most common symptoms for avascular necrosis. However, each individual may experience symptoms differently. Symptoms may include:
- minimal early joint pain
- increased joint pain as bone and joint begin to collapse
- limited range of motion due to pain
The symptoms of avascular necrosis may resemble other medical conditions or bone problems. Always consult your physician for a diagnosis.
In addition to a complete medical history and physical examination, diagnostic procedures for avascular necrosis may include the following:
- imaging procedures, such as:
- x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film; to determine bone changes.
- computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
- radionuclide bone scan - a nuclear imaging technique that uses a very small amount of radioactive material, which is injected into the patient's bloodstream to be detected by a scanner. This test shows blood flow to the bone and cell activity within the bone.
- biopsy - a procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope; to determine if cancer or other abnormal cells are present; to remove tissue from the affected bone.
- functional evaluation of bone - tests, that usually involve surgery, to measure the pressure inside the bone.
Specific treatment for avascular necrosis will be determined by your physician based on:
- your age, overall health, and medical history
- extent of the disease
- location and amount of bone affected
- underlying cause of the disease
- your tolerance for specific medications, procedures, or therapies
- expectations for the course of the disease
- your opinion or preference
The goal of treatment for avascular necrosis is to improve functionality or to stop further damage to the affected bone or joint. Treatments are necessary to keep joints from breaking down, and may include:
- medications (to control pain)
- assistive devices (to reduce weight on the bone or joint)
- core decompression - a surgical procedure to remove inner layers of bone in order to decrease pressure in the bone.
- osteotomy - a surgical procedure to reshape the affected bone.
- bone graft - a surgical procedure to transplant a healthy bone from one area of the patient to the affected/diseased area.
- arthroplasty - total joint replacement.
Other treatments for avascular necrosis may include electrical stimulation, and combination therapies to encourage the growth of new bone.
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