To indicate knee replacement in case of osteoarthritis, its radiographic classification and severity of symptoms should both be substantial. Such radiography should consist of weightbearing X-rays of both knees- AP, Lateral, and 30 degrees of flexion. AP and lateral views may not show joint space narrowing, but the 30 degree flexion view is most sensitive for narrowing. Full length projections are also used in order to adjust the prosthesis to provide a neutral angle for the distal lower extremity. Two angles used for this purpose are: