Abstract

Avascular necrosis of the knee joint is an often missed diagnosis. Like the scaphoid, the knee joint is extremely susceptible to this disease because of the tenuous blood supply of the articular cartilage. This blood supply is easily disrupted, often leaving the proximal portion of the bone without nutrition, leading to osteonecrosis. A disease of the fourth and fifth decades, with the exception of patients suffering from avascular necrosis of the knee joint secondary to collagen vascular disease, avascular necrosis of the knee joint is more common in men. The disease is bilateral in 45% to 50% of cases. Predisposing factors to avascular necrosis of the knee include trauma to the joint, corticosteroid use, Cushing’s disease, alcohol abuse, connective tissue diseases especially systemic lupus erythematosus, osteomyelitis, human immunodeficiency virus infection, organ transplantation, hemoglobinopathies including sickle cell disease, hyperlipidemia, gout, renal failure, pregnancy, and radiation therapy involving the femoral head.

The patient with avascular necrosis of the knee joint complains of pain over the affected knee joint or knee joints that may radiate into the proximal lower extremity. The pain is deep and aching, and the patient often complains of a “catching” sensation with range of motion of the affect knee joint or knee joints. Range of motion decreases as the disease progresses.