Fig. (1) Three views of the Knee #1 model in the knee simulator. Also shown are the femur, tibia, and patella coordinate systems. The z-axis of the femur coordinate is approximately aligned with the long axis of the femur. The y-axis of the femur coordinate is primarily in the anterior-posterior direction while the x-axis is primarily oriented in the medial-lateral direction. Also shown is the posterior view with each of the ligament bundles labeled.