Implementation of a subject-specific paediatric kinematic model of the knee with minimally deformable ligaments in OpenSim

Three-dimensional gait analysis, employing rigid-body motion analysis models, is commonly used for clinical decision-making, treatment, and outcome assessment in children with neuromusculoskeletal disorders, e.g. cerebral palsy. Most multi-segment rigid body models employed in biomechanics use a simplified knee hinge joint that is poorly representative of the complex tibiofemoral joint (TFJ) motion, which must compromise clinical decision-making. More complex TFJ models featuring rigid-spherical articular contacts and ligamentous constraints, with subject-specific and/or generic geometrical parameters, can estimate 6 degree-of-freedom TFJ kinematics during gait in adults [2]. However, no studies have assessed TFJ and ligament kinematics during gait using a rigid-body lower limb model incorporating a fully subject-specific paediatric kinematic knee model with articular contacts and minimally deformable ligaments. This was therefore the aim of the current study.