Patellar motion and dysfunction of its stabilizers in a biomechanical model of the knee joint

Aim. To develop a biomechanical model of the knee joint, including a detailed representation of the patellofemoral segment for the normal anatomy of bones, joints, ligaments and muscles, and study patellar movement during passive knee flexion. Materials and methods. The architecture of the biomechanical model was developed using an open source software system for biomechanical modeling OpenSim. Patellofemoral joint with 6 degrees of freedom, patellar stabilizers – medial patellofemoral ligament (MPFL), medial patellotibial ligament (MPTL), lateral retinaculum (LR), and patellar contact surfaces (facets) were included in the model. Gmsh and Paraview were used to generate the contact surfaces. Simulations of knee passive flexion with consistent patellar stabilizers exclusion were carried out to identify their influence on patellar movement. Results. The presented biomechanical model provides a detailed analysis of the normal dynamics of the patella and the role of different anatomical structures in its functioning and can be used for further experiments investigating of the patellar movement. The experiment involving all ligaments is consistent with the physiological norm. Disabling MPTL has minimal effects on patellar tilt and translation, which aligns with its small size. In contrast, deactivating MPFL results in increased lateral tilt and translation of the patella. Additionally, deactivation of LR components 1 and 2 induces more medial tilt and translation. Deactivating LR components 3 and 4 leads to further lateral translation and slight additional medial tilt. Conclusion. Computational results show that all ligaments contribute to the normal movement of the patella. These findings highlight the importance of stabilizing structures in maintaining patellar stability during knee flexion.