AN OPTIMAL-CONTROL MODEL FOR DETERMINING ARTICULAR CONTACT FORCES AT THE HUMAN KNEE DURING RISING FROM A STATIC SQUAT POSITION

A two-dimensional dynamic model of the knee joint was incorporated int o a four-segment, eight-muscle model of the human body to determine th e muscle, ligament, and articular contact forces transmitted at the kn ee as humans stand up from a static squatting position. Our optimal co ntrol model predicted peak tibiofemoral contact forces 8 times as high as body weight. Furthermore, ligament forces, especially those in the anterior-cruciate, were nearly body weight as knee flexion approached 90 degrees. Ligament and tibiofemoral contact loads were dominated by the forces exerted by muscles during the movement.