Tibiofemoral kinematic analysis using contact model during normal gait

The geometry of the articular surface is extremely important in kinematic analysis, and the 6-DOF joint model is required for an accurate understanding of the functionality of the knee joint in vivo. However, only a few previous studies have utilized the 6-DOF knee joint model, but even in these studies the geometry of the articular surface has been simplified. Thus, we developed a 6-DOF contact model of the human knee joint with realistic geometry, approximated by a non-uniform B-spline, and conducted tibiofemoral kinematic analysis during normal gait using the contact model. The contact point on the femoral condyle shifted posteriorly with knee flexion. In addition, the contact area of the medial condyle was larger than that of the lateral condyle. These results were reasonably consistent with the results of previous studies. According to the results of the tibiofemoral kinematic analyses of six healthy male subjects, the standard deviation of the contact points ranged from ± 0.0145 cm at a 15° flexion to ± 0.1412 cm at 40° on the medial condyle and from ± 0.0046 cm at a 15° flexion to ± 0.1793 cm at 40° on the lateral condyle. The contact points had a very similar pattern as a whole, although six subjects exhibited different gait pattern except for flexion/extension.