Abstract: A method and apparatus for haptic hard surface emulation using a dynamic physical constraint are provided. The movement and position of the dynamic physical constraint is actively controlled in order to emulate a hard surface. The dynamic physical constraint may be controlled by a computer. In another aspect of the invention, the dynamic physical constraint limits the motion of a manipulator joint in space. The position at any time of the dynamic physical constraint is dependent on the position in space of the manipulator's end effector.

Abstract: A method and apparatus for haptic hard surface emulation using a dynamic physical constraint are provided. The movement and position of the dynamic physical constraint is actively controlled in order to emulate a hard surface. The dynamic physical constraint may be controlled by a computer. In another aspect of the invention, the dynamic physical constraint limits the motion of a manipulator joint in space. The position at any time of the dynamic physical constraint is dependent on the position in space of the manipulator's end effector.

Abstract: A method for locating a guide wire axis on a femoral neck comprises the steps of tracking a position and orientation of a femur; registering a frame of reference with respect to the position and orientation of the femur from a first registration probe mounted onto the femur in a predetermined configuration, the frame of reference having preoperative planned data pertaining to the femoral neck; digitizing femoral neck data with respect to the position and orientation of the femur from a second registration probe positioned onto the femoral neck at desired orientations; calculating a position and orientation of the guide wire axis with respect to the position and orientation of the femur as a function of the preoperative planned data and the femoral neck data.

Abstract: A method for locating a guide wire axis on a femoral neck comprises the steps of tracking a position and orientation of a femur; registering a frame of reference with respect to the position and orientation of the femur from a first registration probe mounted onto the femur in a predetermined configuration, the frame of reference having preoperative planned data pertaining to the femoral neck; digitizing femoral neck data with respect to the position and orientation of the femur from a second registration probe positioned onto the femoral neck at desired orientations; calculating a position and orientation of the guide wire axis with respect to the position and orientation of the femur as a function of the preoperative planned data and the femoral neck data.

Abstract: Methods and systems are described to quantitatively determine the degree of soft tissue constraints on knee ligaments and for properly determining placement parameters for prosthetic components in knee replacement surgery that will minimize strain on the ligaments. In one aspect, a passive kinetic manipulation technique is used in conjunction with a computer aided surgery (CAS) system to accurately and precisely determine the length and attachment sites of ligaments. These manipulations are performed after an initial tibial cut and prior to any other cuts or to placement of any prosthetic component. In a second aspect, a mathematical model of knee kinematics is used with the CAS system to determine optimal placement parameters for the femoral and tibial components of the prosthetic device that minimizes strain on the ligaments.