This study investigated the contact pressure and rotation moment by loading of the femoral component and polyethylene insert in internal/external rotation. Five posterior stabilized prosthesis designs were tested to study using an artificial knee joint simulator. The contact pressure and rotational moment were measured at four flexion angle (0 degrees, 45 degrees, 90 degrees and 135 degrees) and five axial tibial rotations (0 degrees, 5 degrees, 10 degrees, 15 degrees and 20 degrees) under the applied loads of 1200N. With an internally rotated tibia, the contact pressure increased significantly and the rotation moment decreased significantly at high flexion. Additionally, Edge loading was found at the polyethylene insert at 20 degrees of tibial rotation. The design and stability with high adaptability in an excessive flexion rotation seem to be necessary.
