Abstract: Preoperative planning method for systematically performing a total hip replacement utilizing CT scan data to size acetabular and femoral components, orient the actabular cup, and equalize leg lengths. The method includes one or more of the steps of selecting acetabular cup size according to dimensions revealed by a certain acetabular CT slice, determining stem size of the femoral component according the scanned dimensions of the medullary canal, reaming the acetabulum and orienting the face of the acetabular cup placed therein according to a reference plane defined by three CT-defined reference points on the acetabulum, equalizing leg lengths by performing the femoral neck osteotomy according the preselected component dimensions and bone/cartilage removal. The invention envisions the use of CT and NMR devices to achieve bony contour definitions.

Abstract: A method is disclosed for the preoperative planning of a total knee replacement. Guide tools having guide members which are adjustable for placement on selected positions of the femur and tibia are used for locating the position of desired bone cuts defined by a cutting guide surface existing on the guide member. Selected regions of the femur and tibia are scanned by computed tomographic techniques to provide images of these regions. The respective centers of the femur head, distal femur, proximal tibia and distal tibia, or ankle joint are determined. The center points are then used to define a mechanical axis relative to which selected cuts are to be made corresponding to selected prostheses to be implanted. The CT scan representations are used to measure the desired location of the guide member cutting surface and the respective locations of guide members adjacent selected bone positions. These guide members are adjusted relative to the cutting surface prior to surgery.