AVN (Avascular Necrosis), also called Osteonecrosis, is a disease that results from the temporary or permanent loss of blood supply to bone. Without a supply of blood, the afflicted areas of bone die, leaving behind what are referred to as “lesions”. From there, the body's natural healing process attempts to breakdown the dead bone and regrow new bone in its place. However, more often than not, the lack of blood supply that caused the onset of the disease has the secondary effect of also inhibiting healing and impeding or preventing new bone growth. If the bone breaks down faster than it regenerates, the end result is often critical deformation or complete collapse.  The risk of bone collapse is much higher in load bearing joints such as hips, knees, shoulders, and ankles.