FORM2D—a mathematical model of the knee

This paper presents a planar model of passive knee motion-FORM2D-utilizing a novel modeling technique. For a given knee flexion, the envelope of passive knee joint motion is determined by applying the femoral translation necessary to minimize the anterior-posterior force in the joint. Unlike existing planar models, FORM2D accounts for all four of the major ligaments (ACL, PCL, MCL and LCL) simultaneously. Results from FORM2D on ligament strain and its clinical applicability are presented.