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 as osteonecrosis, aseptic (bone) necrosis, and ischemic bone necrosis. While it can, by definition, affect any bone, and half of cases show multiple sites of damage, this disease primarily affects the joints at the shoulder, knee, and hip. There are many causes of avascular necrosis such as alcoholism, excessive steroid use, post trauma, Caisson disease (decompression sickness), vascular compression, hypertension, vasculitis, thrombosis, damage from radiation and (very rarely) sickle cell anaemia. In some cases it is idiopathic (no cause is found). The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following codes are used with International Statistical Classification of Diseases and Related Health Problems. ... The International Statistical Classification of Diseases and Related Health Problems (commonly known by the abbreviation ICD) provides codes to classify diseases and a wide variety of signs, symptoms, abnormal findings, complaints, social circumstances and external causes of injury or disease. ... The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. ... Human blood smear: a - erythrocytes; b - neutrophil; c - eosinophil; d - lymphocyte. ... This article is about the body part. ... In human anatomy, the knee is the lower extremity joint connecting the femur and the tibia. ... Bones of the Hip In anatomy, the hip is the bony projection of the femur, known as the greater trochanter, and the overlying muscle and fat. ... Glucocorticoids are a class of steroid hormones characterised by an ability to bind with the cortisol receptor and trigger similar effects. ... This surfacing diver must enter a recompression chamber to avoid the bends. ... For other forms of hypertension, see Hypertension (disambiguation). ... In medicine, vasculitis (plural: vasculitides) is a group of diseases featuring inflammation of the wall of blood vessels due to leukocyte migration and resultant damage. ... Thrombosis is the formation of a clot or thrombus inside a blood vessel, obstructing the flow of blood through the circulatory system. ... Radiation in physics is the process of emitting energy in the form of waves or particles. ...

Although it can happen in any bone, avascular necrosis 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, ankles and the jaw. The disease 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 people between 30 and 50 years of age; about 10,000 to 20,000 people develop avascular necrosis of the head of the femur in the US each year. Orthopaedic doctors most often diagnose the disease except when it affects the jaws, when it is usually diagnosed and treated by dental and maxillofacial surgeons. For other uses of the word bone, see bone (disambiguation). ... The femur or thigh bone is the longest, most voluminous, and strongest bone of the human body. ... Osteonecrosis of the jaws (ONj) is a severe bone disease that affects the jaws, including the maxilla and the mandible. ... Osteonecrosis of the jaws (ONj) is a severe bone disease that affects the jaws, including the maxilla and the mandible. ...

Treatment

Avascular necrosis is especially common in the hip joint. A variety of methods are now used to treat avascular necrosis, the most common being the total hip replacement, or THR. However, THRs have a number of downsides including long recovery times and short life spans. THRs are an effective means of treatment in the geriatric population, however doctors shy away from using them in younger patients due to the reasons above. A new, more promising treatment is metal on metal resurfacing. It is a form of a THR, however in this procedure, only the head of the femur is removed as opposed to a THR in which the entire neck is removed. Metal on metal resurfacing is still experimental in America but has been endorsed in Great Britain as an excellent alternative to a THR. Bone is always undergoing change or remodelling. The bone is broken down by osteoclasts and rebuilt by osteoblasts. Some doctors also prescribe bisphosphonates (e.g. alendronate) which reduces the rate of bone breakdown by osteoclasts, thus preventing collapse (specifically of the hip) due to AVN. Hip replacement is the most successful, cheapest and safest form of replacement surgery. ... In pharmacology, bisphosphonates (also called: diphosphonates) is a class of drugs that inhibits the resorption of bone. ... Alendronate (Fosamax®, Merck) is a bisphosphonate drug used for osteoporosis and several other bone diseases. ...

The amount of disability that results from avascular necrosis 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 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 disease progresses, the bone collapses, and the joint surface breaks down, leading to pain and arthritis.

Notable individuals affected

Avascular necrosis cut short the football and baseball careers of star athlete Bo Jackson [1]. Other sports stars with this condition are cyclist Floyd Landis, winner of the 2006 Tour de France and Brett Favre, NFL quarterback. For other uses of National Football League, see National Football League (disambiguation). ... This article or section does not cite its references or sources. ... This article or section does not cite its references or sources. ... Police officer on a bicycle Cycling is a recreation, a sport and a means of transport across land. ... Floyd Landis (born October 14, 1975) is an American cyclist. ... The 2006 Tour de France was the 93rd Tour de France, taking place from July 1 to July 23, 2006. ... Brett Lorenzo Favre (Rhymes with starve) (born October 10, 1969 in Gulfport, Mississippi) is the starting quarterback for the Green Bay Packers of the National Football League. ... NFL logo For other uses of the abbreviation NFL, see NFL (disambiguation). ...

External links

• National Institute of Health
• Femoral head avascular necrosis
• Center for Joint Preservation in Baltimore Maryland
• Avascular necrosis clinic at Duke
• Osteonecrosis information from Johns Hopkins
• Avascular necrosis program at UCLA
• Center for Osteonecrosis Research
• National Osteonecrosis Foundation
• About core decompression
• Osteonecrosis support group
• Differential diagnosis for osteonecrosis
• AVN information from Merck
• Merck manual discusses AVN
• AVN etiology
• AVN and Hip resurfacing
• Osteonecrosis program at Florida Hospital
• Osteonecrosis research at the Jewish Hospital in Cincinnati
• University Hospital in New Jersey
• Orthopedic Sciences
• Zimmer trabecular implant
• Beijing Emperor Special Hospital of Femur Head Necrosis