Osteonecrosis
What causes it?
Bone death is the result of diminished arterial blood supply. If blood flow is completely interrupted and not promptly restored, bone death ensues. Normally, bone breaks down and rebuilds continuously. In the course of osteonecrosis, however, the healing process is ineffective due to the poor blood supply and the bone tissues break down faster than the body can repair them.
Several different factors can lead to the interrupted blood supply and development of osteonecrosis.
- Corticosteroid use: People who have diseases that may necessitate large doses of steroids (lupus, rheumatoid arthritis, inflammatory bowel disease, vasculitis) are at increased risk. Long-term systemic corticosteroid use is associated with 35 percent of all cases of nontraumatic osteonecrosis. Steroid medications can increase fatty marrow and increase the formation of fatty substances, which block arteries.
- Injuries: Fractures or dislocations can produce osteonecrosis if the arteries supplying the bones are damaged. More than 20 percent of people who dislocate their hip joint will develop osteonecrosis.
- Blocked blood vessels: Anything that can block your arteries can cause osteonecrosis, including accumulation of fat particles in the vessels, abnormal red blood cells, sickle cell disease, decompression sickness (the bends), blood coagulation disorders, small-vessel vasculitis, arteriolar thrombosis, venous occlusion, microembolism, etc.
- Increased pressure in the bone: Bone is essentially incapable of expanding, so increased pressure can cut off blood supply.
- Gaucher’s disease: an inherited metabolic disorder
- Alcohol abuse: Drinking excessive amounts of alcohol induces the production of fatty substances that may block blood vessels, thereby decreasing blood supply.
- Pancreatitis: inflammation of the pancreas
- Radiation treatments and chemotherapy
