Non-invasive techniques for musculoskeletal model calibration

Subject-specific musculoskeletal models are mandatory to conduct efficient analyses of muscle and joint forces involved in human motion. Thus, proper model calibration at geometrical, inertial, and muscular levels is critical. This article present a threefold approach for model calibration that can be easily deployed in any biomechanical lab equipped with classical motion analysis facilities. First, motion capture data is used to calibrate geometrical parameters of the model (bones lengths, joint centers, and joint orientations). The calibration minimizes the distance between real and reconstructed trajectories of markers. Second, motion capture and force platforms data are used to calibrate inertial parameters of the model. The calibration minimizes the residual forces arising from the model inertial inaccuracies in the dynamics of the system. Last, isokinetic ergometer data are used to calibrate muscular parameters. The calibration minimizes the distance between the experimental maximal isometric torque curve and the simulated one for a given joint. Examples are provided throughout the paper and results are discussed. A focus is made on the idea of using such methods as a tool in any motion analysis lab.