Avascular necrosis, or osteonecrosis, is the name given to bone death, a condition that occurs when the blood supply to an area of the bone is cut off either temporarily or permanently.
Bone is living tissue, which is supplied by many blood vessels. Bone that does not have a supply of blood (avascular) for an extended period of time becomes brittle and eventually collapses. This can lead to severe cases of arthritis and dysfunction in the affected joint.
The thighbone (femur) is the most commonly affected bone, followed by the shoulder. Other large joints, including the knee, ankle and wrist, can also be affected.
This condition is also known as ischaemic bone necrosis, aseptic necrosis and bone infarction.
Healthy femoral bone alongside femoral bone with avascular necrosis.
A connecting surface or tissue between two bones.
The inside of the bones consists of a strong, honeycomb-like structural tissue, called trabecular tissue. This tissue forms a lattice pattern along the bone stress lines next to bone marrow cavities. Without a fresh blood supply, the trabecular tissue ceases to provide structure or strength to the bone, which often causes the bone to collapse. Certain bones are more at risk, as they rely only on one or very few blood vessels for their blood supply. The ball-shaped end of the femur, which forms part of the hip joint, relies on blood vessels that pass through the thinner shaft of the femur, which can be broken during a fall.
The most common causes of avascular necrosis are as follows:
Injury to the bone, such as a fracture or dislocation that interrupts the blood supply to the bone by severing or damaging the blood vessels, can result in avascular necrosis.
The spongy, vascular or fatty tissue found inside bones, responsible for producing blood cells.
A medication-based treatment, usually used in the treatment of cancers. There are numerous, different types of chemotherapy drugs that can be prescribed by a specialist. These can commonly be used alongside other cancer treatments such as surgery and radiotherapy.
A complete or incomplete break in a bone.
A treatment that uses ionizing radiation to kill or control growth of malignant cancer cells.
A displacement of a body part, such as a joint, from its normal position.
There are several risk factors that can result in avascular necrosis:
A group of drugs that prevent the loss of bone mass by reducing the normal turnover of bone. They are used to treat osteoporosis and other bone diseases.
A medication-based treatment, usually used in the treatment of cancers. There are numerous, different types of chemotherapy drugs that can be prescribed by a specialist. These can commonly be used alongside other cancer treatments such as surgery and radiotherapy.
A complete or incomplete break in a bone.
The transfer of an organ from one individual to another This can be from a live donor, or from someone who has died that previously expressed their wish for their organs to be donated.
Inflammation of the pancreas.
A treatment that uses ionizing radiation to kill or control growth of malignant cancer cells.
A hereditary form of anemia in which a defective form of hemoglobin cause red blood cells to be an abnormal crescent shape. This causes the cells to break down prematurely, which can then lead to anemia.
A displacement of a body part, such as a joint, from its normal position.
Gaucher disease is a rare genetic condition that results in the abnormal accumulation of fatty cells in numerous organs within the body. A potential complication is when the fatty cells accumulate in bone marrow, restricting normal blood flow and thus leading to bone death.
Osteonecrosis of the jaw is a rare and serious condition, in which the cells of the jawbone begin to die. This can sometimes develop following radiotherapy to the head and neck area, bisphosphonates treatment, or after a tooth extraction while having either of the two treatments. The symptoms of osteonecrosis of the jaw include severe pain and development of an infection or pus in the exposed area.
Spontaneous osteonecrosis of the knee is when a section of the knee bone dies. It is more common in women and has been linked to osteoporosis. The symptoms usually start in the inner knee, and include localized swelling and tenderness.
Perthes' disease, also known as coxa plana or Legg-Calve-Perthes disease, is a type of avascular necrosis that affects the hip joints of children - most often boys - aged between 3-11 years, for reasons that are currently unknown. During this condition, there is a reduced supply of blood to the round head of the thighbone, known as the femoral head, which fits into the hip socket. This causes loss of bone cells and softening and collapse of the hip joint, which results in pain, limping and reduced movement.
However, most children will recover fully and without complications, using treatments such as braces, pain-relief medications and rest from high-impact activities.
A group of drugs that prevent the loss of bone mass by reducing the normal turnover of bone. They are used to treat osteoporosis and other bone diseases.
Entry into the body of microorganisms that can reproduce and cause disease.
A connecting surface or tissue between two bones.
A bodily fluid that is the result of an inflammatory response at an infection site. Its color can range from whitish to yellow to green, depending on the composition. Pus is mainly composed of dead bacteria, white blood cells and cellular debris.
A treatment that uses ionizing radiation to kill or control growth of malignant cancer cells.
During the first stages of avascular necrosis, there are often no signs or symptoms. Once the bone damage worsens, however, the following symptoms may develop:
The area where the abdomen joins the thighs.
A doctor can suspect avascular necrosis based on a person's medical history and a physical examination. To help confirm the diagnosis, the following tests may also be carried out.
An X-ray is usually the first recommended imaging test for any bone condition. However, as X-rays are not always useful for detecting avascular necrosis in its early stages, they are used more often to track the condition's progression.
Magnetic resonance imaging (MRI) creates an image that can detect changes in the density and structure of your bones. MRI is considered the best option for diagnosing avascular necrosis, as the scans can reveal any chemical changes in the bone marrow, as well as the presence of abnormal tissue, prior to development of any symptoms.
A computerized tomography (CT) scan can provide detailed imaging of the interior bone structure, revealing any areas of avascular necrosis.
In a bone scan a radioactive substance is injected into the bloodstream. Its circulation is detected by a gamma camera, revealing any problem with blood flow to the bones.
A bone biopsy can provide supportive evidence of avascular necrosis, but as it requires surgery, non-invasive tests such as MRI are usually preferred.
The spongy, vascular or fatty tissue found inside bones, responsible for producing blood cells.
A scan that uses X-rays to create a 3D image of the body. This can detect abnormalities more effectively than a simple X-ray can.
A type of imaging that uses a magnetic field and low-energy radio waves, instead of X-rays, to obtain images of organs.
A scan that uses ionizing radiation beams to create an image of the body’s internal structures.
A camera used in imaging scans of the body. It detects radiation from radioactive material that has been introduced into the person's body to highlight areas of interest.
The type of treatment offered will depend on the level of damage in the bones, age, activity levels, life expectancy and presence of other health conditions. If avascular necrosis is in its early stages, more treatment options are available than in cases of severe avascular necrosis. Treatment options will typically be decided by a specialist and can include the following options:
Protected weight-bearing involves taking weight off the affected joint by using supportive aids such as crutches. This treatment can help with pain relief, but will not cure the condition.
Currently, there is no medication that directly stops the progress of or cures avascular necrosis. However, some medications may be beneficial early in the condition. These include:
Pulsed electrical stimulation has been used to encourage bone growth, and some evidence has suggested that it is effective in the treatment of early-stage avascular necrosis.
Hyperbaric oxygen treatment involves entering a pressurized chamber where the lungs can absorb up to three times more oxygen than normal. The treatment has been shown to provide significant improvements in pain, range of mobility and bone healing in some cases of early-stage avascular necrosis. [2]
Working with a physiotherapist to design and use strengthening exercises may be helpful with increasing flexibility and range of movement.
Surgery is not typically recommended, except in cases of bone damage or collapse. Surgical procedures include:
This procedure involves taking healthy bone from another part of the body and implanting it into the area affected by avascular necrosis. This can be done together with a core decompression procedure.
This procedure involves replacing a section of dead bone with a bone graft. Historically, bone core decompression was used as a diagnostic procedure to test bone marrow density, but as patients reported pain relief after the procedure, it became a therapy. It has been shown to regenerate bone growth and prevent the exterior of the bone from collapsing, eliminating the need for a joint replacement.
This less common procedure involves cutting away the dead bone from a weight-bearing area and reshaping the bone to allow healthy bone and cartilage to bear the weight instead.
If the avascular necrosis is in its later stages and the bone has collapsed, a complete joint replacement may be required. The surgeon will replace damaged bone with a prosthetic joint. Both the ball and socket of the hip may be replaced.
A group of drugs that prevent the loss of bone mass by reducing the normal turnover of bone. They are used to treat osteoporosis and other bone diseases.
The spongy, vascular or fatty tissue found inside bones, responsible for producing blood cells.
A tough, flexible connective tissue found in various parts of the body including the joints and larynx.
A body’s protective immune response to injury or infection. The accumulation of fluid, cells and proteins at the site of an infection or physical injury, resulting in swelling, heat, redness, pain and loss of function.
Cardozo, J.B., Andrafe, D.M. and Santiagi, M.B. (2008) The use of bisphosphonate in the treatment of avascular necrosis: a systematic review. Clinical Rheumatology 27:685-688.
Camporesi, E.M., Vezzani, G. and Bosco, G. (2010) Hyperbaric oxygen therapy in femoral head necrosis. The Journal of Arthroplasty 25:118-123.
If left untreated, avascular necrosis can lead to bone collapse, arthritis and physical disability.
Avascular necrosis is a condition that requires medical treatment in its early stages, to try and reduce the chances of bone collapse or surgery. Though it cannot be cured, if detected early on, the symptoms can be managed and bone damage minimized.
In many cases, avascular necrosis cannot be prevented, but you can lower your risk by avoiding long-term use of corticosteroids, if you can, and avoiding excessive alcohol consumption.
A medication that resembles the cortisol hormone produced in the brain. It is used as an anti-inflammatory medication.