Avascular Necrosis of the Knee
What it is
Avascular necrosis (AVN), also called osteonecrosis, aseptic necrosis, or ischemic bone necrosis, is a condition that occurs when there is loss of blood to the bone. Because bone is living tissue that requires blood, an interruption to the blood supply causes bone to die. If not stopped, this process eventually causes the bone to collapse.
Symptoms of Avascular Necrosis
In its early stages, AVN typically cause no symptoms; however, as the disease progresses it becomes painful. At first you may experience pain pain when you put pressure on the affected bone. Then, pain may become more constant. If the disease progresses and the bone and surrounding joint collapse, you may experience severe pain that interferes with your ability to use your joint. The time between the first symptoms and collapse of the bone may range from several months to more than a year.
Source from AAOS, Viewmedica, WebMD