Development of a musculoskeletal model of the knee joint to predict articular contact patterns during a loaded squat movement

Computational models are a current way to study specific behavior of healthy or pathological tissue or the mechanics of joints. Simulating the native anatomical structures and kinematics are two of the most important tasks to achieve reliable results. It is especially challenging for the knee as it is one of the most complex joint in the human body. It consists of two articulations, one between femur and tibia and one between femur and patella. This thesis estimates the patellofemoral and tibiafemoral contact pattern during a simulated squat movement. This is achieved by using a musculoskeletal, loaded knee model controlled by muscle activation. The flexion is performed by the elongation of the rectus femoris muscle. The knee model consists of femural, patellar and tibial articular cartilage, the menisci, anterior and posterior cruciate ligaments and the medial and lateral collateral ligaments. Contours of all soft tissues were segmented on the magnetic resonance imaging slides and imported into Solidworks (SolidWorks Corp., Concord, MA, United States) to build up the 3D geometry. A previous thesis already reconstructed the tibia, femur, fibula and patella bone geometry from Computed tomography images, so cartilage and menisci were done during this study. Abaqus (Dassault Systèmes Simulia Corp., Rhode Island, USA) was used for finite element modeling. The cartilage and menisci were meshed with hexahedral elements and bones were modeled as rigid bodies. An explicit solver was chosen for the numerical simulation and the squat movement should be performed quasi static. Mass scaling was required to reduce computational time and a global damping was used to minimize the oscillations. But sill, the squat movement could not be performed.