The interaction and load sharing between muscles, ligaments and articulating surfaces is crucial for the stability of the knee. The aim of the present work is to develop an effective multibody dynamics-based model that allows a quick subject-specific assessment of ligaments, muscular behavior and contact forces.
This paper shows the results of ‘quasi-static’ simulations of a squat movement between 0° and 90° of flexion in gravitational force field. During this movement the lengths of anterior cruciate ligament (ACL) and lateral collateral ligament (LCL) decreased up to 21% and 10.5%, respectively, while the lengths of medial collateral ligament (MCL) and posterior cruciate ligament (PCL) increased. Quadriceps muscle force at equilibrium increased during flexion reaching a value of 3.88 body weight (BW) at 90°
of flexion. Tibio-femoral contact forces changed non-linearly with joint angle and achieved a maximum value of 4.58 BW at 90° of flexion.
Once completely developed this model could be used to investigate the effect of several key factors in the surgical planning that could affect the knee biomechanics and the
results of the intervention
