Range of motion method D’Lima proposed relatively loose criteria considered acceptable in modern times: anterior flexion >110°, posterior extension >30°, internal rotation >30° and external rotation >40° in the 90° flexion position of the hip; this criterion can be achieved intraoperatively Joint anterior tilt angle method: Coplanar test After hip resetting, the hip is extended at 0°, the knee is flexed at 90°, and the thigh is parallel to the ground. Observe from the head side, internally rotate the thigh so that the neck of the femoral prosthesis is perpendicular to the plane of the acetabular cup prosthesis (the edge of the femoral head prosthesis is parallel to the edge of the liner, and the exposed area of the anterior and posterior parts of the femoral head prosthesis is equal), at this time the angle made by the lower leg and the horizontal plane (the angle of internal rotation of the hip joint) is the joint anterior tilt angle after hip resetting, extend the hip 0°, bend the knee 90°, the thigh is parallel to the ground, observe from the head side, internally rotate the thigh so that the femur The neck of the prosthesis is perpendicular to the plane of the acetabular cup prosthesis (the edge of the femoral head prosthesis is parallel to the edge of the liner, and the exposed area of the anterior and posterior parts of the femoral head prosthesis are equal), and the angle between the lower leg and the horizontal plane (the angle of internal rotation of the hip joint) is the joint anteversion angle. The relative position of the liner and the femoral head prosthesis is observed in the neutral position with the hip joint extended and rotated, and the angle between the edge of the liner and the projection of the edge of the femoral head prosthesis should be between 30 If the angle between the edge of the liner and the edge projection of the femoral head prosthesis is less than 30°, the joint anterior tilt angle is small and posterior dislocation or limited hip flexion is likely to occur. If the angle is greater than 45°, the joint anterior tilt angle is large, which is prone to anterior dislocation or hip extension restriction Hip flexion 45° method: 1. The standard for determining the appropriate angle of the prosthesis is: when the hip is flexed at 45°, the edge of the femoral head trial mold is parallel to the edge of the liner trial mold or the edge of the acetabular cup trial mold (when there is no liner trial mold), i.e. the front and rear exposed areas of the femoral head trial mold are equal. 2.If the edge of the femoral head specimen is parallel to the edge of the liner specimen when the hip flexion is less than 45° (for example, 20° hip flexion), and the front part of the femoral head specimen is less exposed and the rear part is more exposed when the hip flexion is 45°, it means that the anterior tilt of the acetabular cup specimen is small and the anterior tilt of the acetabular cup specimen needs to be increased. If the edge of the femoral head specimen is parallel to the edge of the liner specimen when the hip is flexed more than 45° (e.g. 70°), and the anterior part of the femoral head specimen is more exposed and the posterior part is less exposed when the hip is flexed 45°, it means that the anterior tilt of the acetabular cup specimen is large, and the anterior tilt of the acetabular cup specimen should be reduced.