Osteoarthritis and osteonecrosis (avascular necrosis) are two diferent problems. Osteoarthritis occurs with when the cartilage wears thin and degrades. It is thought to primarily a cartilage problem although recently some investigators have raised the theory that collapse of bone at the cartilage interface may also contribute. Osteonecrosis occurs when the bone does not get enough blood supply and dies. This occurs most commonly after trauma to the joint. Patients with certain blood disorders, patients with lupus or who are taking high doses of prednisone are also at risk for osteonecrosis. The confusion comes when a joint is badly degenerated or “endstage”. A that point it is often impossible to distinguish between the two problems.
About Alan Matsumoto, M.D.
Part-time Faculty, Division of Rheumatology
Johns Hopkins University