About avascular necrosis of bone

What is avascular necrosis of bone?

Osteonecrosis, also known as 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. This disease also is known, aseptic necrosis, and ischemic bone necrosis.

Although it can happen in any bone, osteonecrosis most commonly affects the ends (epiphysis) of long bones such as the femur, the bone extending from the knee joint to the hip joint. Other common sites include the upper arm bone, knees, shoulders, and ankles. The disease may affect just one bone, more than one bone at the same time, or more than one bone at different times. Orthopaedic doctors most often diagnose the disease.

The amount of disability that results from osteonecrosis depends on what part of the bone is affected, how large an area is involved, and how effectively the bone rebuilds itself. The 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 osteonecrosis, however, the healing process is usually ineffective and the bone tissues break down faster than the body can repair them. If left untreated, the disease progresses, the bone collapses, and the joint surface breaks down, leading to pain and arthritis.



What are the symptoms for avascular necrosis of bone?

Arthritis symptom was found in the avascular necrosis of bone condition

Pain can be mild or severe. It usually develops gradually. Pain associated with avascular necrosis of the hip might center on the groin, thigh or buttock. Besides the hip, the shoulder, knee, hand and foot can be affected.

Some people develop avascular necrosis on both sides, such as in both hips or in both knees.



What are the causes for avascular necrosis of bone?

Avascular necrosis occurs when blood flow to a bone is interrupted or reduced. Reduced blood supply can be caused by:

  • Joint or bone trauma. An injury, such as a dislocated joint, might damage nearby blood vessels. Cancer treatments involving radiation also can weaken bone and harm blood vessels.
  • Fatty deposits in blood vessels. The fat (lipids) can block small blood vessels. This can reduce blood flow to bones.
  • Certain diseases. Medical conditions, such as sickle cell anemia and Gaucher's disease, also can lessen blood flow to bone.

Sometimes the cause of avascular necrosis not brought on by trauma isn't fully understood. Genetics combined with overuse of alcohol, certain medications and other diseases likely play a role.



What are the treatments for avascular necrosis of bone?

The goal is to prevent further bone loss.

Medications

In the early stages of avascular necrosis, certain medications may help ease symptoms:

  • Nonsteroidal anti-inflammatory drugs (NSAIDs). Over-the-counter medications like ibuprofen (Advil, Motrin IB, others) or naproxen sodium (Aleve) might help relieve pain associated with avascular necrosis. Stronger NSAIDs are available by prescription.
  • Osteoporosis drugs. These types of medications might slow the progression of avascular necrosis, but the evidence is mixed.
  • Cholesterol-lowering drugs. Reducing the amount of cholesterol and fat in the blood might help prevent the vessel blockages that can cause avascular necrosis.
  • Medications that open blood vessels. Iloprost (Ventavis) might increase blood flow to the affected bone. More study is needed.
  • Blood thinners. For clotting disorders, blood thinners, such as warfarin (Jantoven), might prevent clots in the vessels feeding the bones.

Therapy

Your health care provider might recommend:

  • Rest. Restricting physical activity or using crutches for several months to keep weight off the joint might help slow the bone damage.
  • Exercises. A physical therapist can teach exercises to help maintain or improve the range of motion in the joint.
  • Electrical stimulation. Electrical currents might encourage the body to grow new bone to replace the damaged bone. Electrical stimulation can be used during surgery and applied directly to the damaged area. Or it can be administered through electrodes attached to the skin.

Surgical and other procedures

Because most people don't develop symptoms until avascular necrosis is advanced, your health care provider might recommend surgery. The options include:

  • Core decompression. A surgeon removes part of the inner layer of bone. Besides reducing pain, the extra space inside the bone triggers the production of healthy bone tissue and new blood vessels.
  • Bone transplant (graft). This procedure can help strengthen the area of bone affected by avascular necrosis. The graft is a section of healthy bone taken from another part of the body.
  • Bone reshaping (osteotomy). A wedge of bone is removed above or below a weight-bearing joint, to help shift weight off the damaged bone. Bone reshaping might help postpone joint replacement.
  • Joint replacement. If the affected bone has collapsed or other treatments aren't helping, surgery can replace the damaged parts of the joint with plastic or metal parts.
  • Regenerative medicine treatment. Bone marrow aspirate and concentration is a newer procedure that might help avascular necrosis of the hip in early stages. During surgery, the surgeon removes a sample of dead hipbone and inserts stem cells taken from bone marrow in its place. This might allow new bone to grow. More study is needed.



What are the risk factors for avascular necrosis of bone?

Risk factors for developing avascular necrosis include:

  • Trauma. Injuries, such as hip dislocation or fracture, can damage nearby blood vessels and reduce blood flow to bones.
  • Steroid use. Use of high-dose corticosteroids, such as prednisone, is a common cause of avascular necrosis. The reason is unknown, but some experts believe that corticosteroids can increase lipid levels in the blood, reducing blood flow.
  • Drinking too much alcohol. Having several alcoholic drinks a day for several years also can cause fatty deposits to form in blood vessels.
  • Bisphosphonate use. Long-term use of medications to increase bone density might contribute to developing osteonecrosis of the jaw. This rare complication has occurred in some people treated with high doses of these medications for cancers, such as multiple myeloma and metastatic breast cancer.
  • Certain medical treatments. Radiation therapy for cancer can weaken bone. Organ transplants, especially kidney transplants, also are associated with avascular necrosis.

Medical conditions associated with avascular necrosis include:

  • Pancreatitis
  • Gaucher's disease
  • HIV/AIDS
  • Systemic lupus erythematosus
  • Sickle cell anemia
  • Decompression sickness, also known as divers' disease or the bends
  • Certain types of cancer, such as leukemia



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