Osteonecrosis of the Knee, is the result of vascular arterial insufficiency to the medial femoral condyle of the knee resulting in necrosis and destruction of bone. It is often unilateral and can be associated with a meniscal tear.
The condition is usually characterized by a sudden onset of knee pain, worse at night, or during weight-bearing such as standing or running. Nevertheless, it can also occur during rest or without any weight-bearing.
About 94% of the cases affect the medial condyle of the femur. This is because the blood supply for the medial condyle is less than the blood supply for the lateral condyle of the femur. The condition may deteriorate, causing asymmetrical walking or running pattern. Sometimes, they have a history of osteoporosis or osteopenia.