Avascular necrosis is also sometimes known as osteonecrosis. It is a condition in which bone tissue dies because of blood loss to nourish and support it. Without an adequate supply of blood, bones can develop tiny breaks and can eventually collapse.
Circulation to bone tissue leading to avascular necrosis can be interrupted by a dislocated joint or by a fracture of the bone. Avascular necrosis has also been associated with the long-term use of corticosteroid medications when taken in high doses and excessive alcohol intake.
Although any individual can develop avascular necrosis, it is most likely to develop in people who are between 30 and 60 years of age. Because it is most common in this age group, it can result in significant long-term complications.
Avascular necrosis causes
Avascular is a term that means “without blood vessels.” Avascular necrosis is a condition that occurs when the flow of blood to a bone is reduced or is interrupted. This blood flow reduction can be due to:
- Trauma to a bone or joint: Injuries like joint dislocations or fractures can damage blood vessels near the injury site. Radiation used in the treatment of cancer can also damage blood vessels and injure bones.
- Deposits of lipids: Fats, also called lipids, can block blood vessels, restrict blood flow to the bones, and cause avascular necrosis.
- Certain medical conditions: Diseases like sickle cell anemia can result in reduced blood flow to bone tissue.
In approximately one-fourth of the cases of avascular necrosis, the cause of the restriction in blood flow is unknown.
Avascular necrosis risk factors
There is a group of factors that can increase a person’s risk for developing avascular necrosis. These include:
- Traumatic injuries: These include fractures or joint dislocations. Injuries like these can interrupt blood flow to the bones due to damage caused to blood vessels near the injury site.
- Use of steroids: The use of corticosteroids in high doses is the leading cause of non-traumatic avascular necrosis. The exact way this happens is not known. Still, it may be due to the steroids increasing the levels of lipids in the bloodstream, which then restrict blood flow and cause avascular necrosis to occur.
- Excessive alcohol intake: The long-term excessive alcohol intake may also lead to the formation of fatty deposits in the blood vessels, causing restricted blood flow.
- Use of bisphosphonates: Bisphosphonates are drugs used to help increase bone density. These may increase the risk of avascular necrosis of the jaw. It has occurred in some patients who have taken these medications as a treatment for cancer. The risk is lower when these drugs are used to treat women with osteoporosis.
- Certain medical treatments: Kidney transplantation and other organ transplantation have been associated with an increased risk for avascular necrosis. Radiation treatments given as a treatment for cancer also weaken bone tissue and can damage blood vessels.
Medical conditions associated with a greater risk for avascular necrosis include:
- Sickle cell anemia
- Systemic lupus erythematosus
- Gaucher’s disease