Mobile-bearing total knee arthroplasty has potential advantages over fixed- bearing prostheses that may lead to an improvement of the range of motion and inferior long-term polyethylene wear. However, the potential disadvantages include the dislocation of the PE tibial insert that is usually the result of quadriceps deficiency, ligament laxity and traumatic events. Therefore, 2 goals are pursued in this project. In a first step, an analysis of the existing literature will let to find out the causes of bearing dislocation. In a second step, some of these causes will be reproduced in a 3D musculoskeletal model of the lower limb to investigate the effect on the tibial insert of the knee prosthesis FIRST (Symbios, Switzerland).