What Causes Avascular Necrosis?
There are several
avascular necrosis causes, some of which are related to trauma (trauma-related avascular necrosis) and some of which are not related to trauma (nontraumatic avascular necrosis). Steroid medicines and alcohol use are the two most common causes of nontraumatic avascular necrosis.
Traumatic Causes of Avascular Necrosis
When a joint is injured, as in a fracture or dislocation, the blood vessels may be damaged. This can interfere with the blood circulation to the bone and lead to trauma-related avascular necrosis. Studies suggest that this type of avascular necrosis may develop in more than 20 percent of people who dislocate their hip joint.
Nontraumatic Causes: Steroid Medications
Corticosteroids, such as
prednisone, are commonly used to treat diseases in which there is inflammation, such as:
- Systemic lupus erythematosus (lupus or SLE)
- Rheumatoid arthritis (RA)
- Inflammatory bowel disease (IBD)
- Vasculitis.
Studies suggest that long-term systemic (oral or intravenous) corticosteroid use is associated with 35 percent of all cases of nontraumatic avascular necrosis; however, limited (short-term) use of steroids does not seem to carry the same degree of risk. If you are concerned about unwanted effects of steroid use, discuss this with your healthcare provider.
Doctors aren't sure exactly why the use of corticosteroids sometimes causes avascular necrosis. They may interfere with the body's ability to break down fatty substances. These substances then build up in and clog the blood vessels, causing them to narrow. This reduces the amount of blood that gets to the bone. Some studies suggest that corticosteroid-related avascular necrosis is more severe and more likely to affect both hips (when occurring in the hip) than avascular necrosis resulting from other causes.
