Knee tensioner-balancer and method

A method of evaluating a human knee joint which includes a femur bone, a tibia bone, and ligaments, wherein the ligaments are under anatomical tension to connect the femur and tibia together, creating a load-bearing articulating joint, the method comprising:

• inserting into the knee joint a tensioner-balancer that includes a femoral interface surface, and at least one force sensor;
• providing an electronic receiving device;
• moving the knee joint through at least a portion of its range of motion;
• while moving the knee joint, using the electronic receiving device to collect data from the at least one force sensor;
• processing the collected force data to produce a digital geometric model of the knee joint, wherein the digital geometric model includes:
• a medial spline representing a locus of points of contact of a medial condyle of the femur with the femoral interface surface, over a range of knee flexion angles, each of the points of contact characterized by a location, a direction, and a first and second derivative;
• and
• a lateral spline representing a locus of points of contact of the femur with the femoral interface surface over a range of knee flexion angles, each of the points of contact characterized by a location, a direction, and a first and second derivative;
• and
• storing the digital geometric model for further use.