andlt;strongandgt;Prosthetic knee joint.andlt;/strongandgt; Coloured profile X-ray of apatient with a prosthetic knee (white, centre).The artificial joint consists of two halves, onehalf attached to the femur (thigh bone) above theknee and the other half attached to the tibia(shin bone) below the knee. This is a hinge joint, which also allows a degree of rotation, imitatingthe mobility of the natural joint. Prosthetic kneejoints are used to replace joints that have becomestiff and painful as a result of arthritis orinjury. Knee replacements can dramatically improveknee joint mobility, and can offer years ofindependence. The artificial components can, however, loosen with time.