Avascular necrosis (AVN) (also known as osteonecrosis, bone necrosis, bone infarction, aseptic necrosis, and ischemic necrosis) is a condition in which the bone "dies" as a result of a loss of circulation to an area of bone tissue. (The word osteonecrosis is Latin for "bone death.") In extreme cases, it can result in the collapse of a segment of bone. When the surface of a joint is involved, it may lead to rapidly progressive osteoarthritis.
Avascular necrosis can occur as a result of an injury that interrupts the blood supply, such as in AVN of the hip after a fracture of the upper femur (thighbone). Other causes include the use of systemic steroids as well as certain inflammatory diseases, such as lupus. The exact mechanism for loss of circulation in these circumstances is not well understood.
The most common body parts affected by AVN are the hip, knee, spine, shoulder and wrist. In cases of AVN of the hip, it is very important to diagnose and treat early in order to prevent disability. Treatment varies considerably, depending on the location and severity, but the goal of initial treatment is to prevent collapse of the joint surface. In the advanced stages that result in painful arthritis, a hip replacement may become necessary.
For information on AVN of the knee, see Osteonecrosis of the Knee: An Overview.