Investigation of the biomechanic function of cruciate ligaments using kinematics and geometries from a living subject during step up/down motor task

The modeling approach is the only possible way to estimate the biomechanic function of the different anatomical sub-structures of the knee joint in physiological conditions. Subject-specific geometry and kinematic data were the foundations of the 3D quasi-static model adopted for the present work. A previously validated cruciate ligaments model was implemented taking the anatomical twist of the fibers into account. The anatomical load components, developed by the modeled ligaments, were estimated during step up/down motor tasks. The anterior cruciate ligament never developed force, along every directions. The posterior cruciate ligament developed increasing forces with the increasing of the flexion angle until at about 70° of flexion. Bigger repeatability in the force curves was obtained in extension with respect to the flexion movement. In conclusion the proposed model was effective in evaluating loads in the anterior and posterior cruciate ligament during the execution of daily living activities.