The infection that causes osteomyelitis often is in another part of the body and spreads to the bone via the blood. Affected bone may have been predisposed to infection because of recent trauma.

In children, the long bones are usually affected. In adults, the vertebrae and the pelvis are most commonly affected. Bone infection can be caused by bacteria or by fungus. When the bone is infected, pus is produced within the bone, which may result in an abscess. The abscess then deprives the bone of its blood supply.

Chronic osteomyelitis results when bone tissue dies as a result of the lost blood supply. Chronic infection can persist intermittently for years.

Risk factors are recent trauma, diabetes, hemodialysis, and intravenous drug abuse. People who have had their spleen removed are also at higher risk for osteomyelitis.

The incidence of osteomyelitis is 2 in 10,000 people.