Total knee replacement, a surgical procedure in which damaged parts of the knee joint are replaced with artifical parts. The surgery is done by separating the muscles and ligaments around the knee to expose the inside of the joint. The ends of the thigh bone (femur) and the shin bone (tibia) are removed as is often the underside of the kneecap (patella). The artificial parts are then cemented into place. The new knee typically has a metal shell on the end of the femur, a metal and plastic trough on the tibia, and sometimes a plastic button in the kneecap. Total knee replacement may be done on people, usually over 55, whose knees have been damaged by arthritis, trauma, or other destructive diseases of the joint resulting in severe limiting knee pain and significant stiffness, instability (constant giving way) and deformity (lock-knees or bowlegs) of the knee.