Comparison of two musculoskeletal models to evaluate glenohumeral joint kinematics and dynamics

The musculoskeletal models have been used to estimate simultaneously the internal forces and the joint kinematics during motion to avoid intrusive methods to diagnose glenohumeral instability. The Holzbaur model and the Wu model have the main algorithms to calculate the joint kinematics and dynamics that are used in most of the musculoskeletal models to evaluate mobility and instability. No research has been done to compare the two main shoulder models’ algorithms to evaluate shoulder mobility and have been reported to evaluate stability. The estimation of range of motion and the joint reaction forces are fundamental to find quantitative parameters to evaluate stability and mobility. The shoulder mobility has been evaluated with standardized motion. From these, standardized motions, abduction has been used as a clinical test to evaluate kinematic patterns to differentiate from healthy subjects and subjects with anterior-posterior instability. Nevertheless, the lack of evidence of the comparison of both models has not been enough to find what model is better to evaluate joint kinematics and dynamics. The joint kinematics and dynamics are essential to differentiate between healthy and pathological subjects. Through the use of musculoskeletal models, the computation algorithms are used to estimate the joint joint kinematics, moments, and joint contact forces that are calculated based on experimental data. Nevertheless, the musculoskeletal models need to be ranked, and evaluated with experimental data to identify the best models to evaluate joint kinematics and dynamics. The direct measurement of joint reaction forces with biomodular implants [1] are essential to compare the joint reaction forces that are estimated with both models. The biomodular implants have been evaluated in patients with total shoulder replacement to have a better approach to estimate the joint contact forces with musculoskeletal models. The comparison of musculoskeletal models will help to evaluate joint kinematics and dynamics for healthy subjects and patients with other surgical procedures. This research is designed to verify the models’ capability to estimate joint contact forces with the aim of improving the accuracy to improve the detection of quantitative parameters to assess glenohumeral joint instability. The diagnosis of glenohumeral joint instability has been quantified with the estimation of joint kinematics and dynamics with musculoskeletal models. The comparison of the joint reaction forces between the two models can improve the methods to detect the algorithm’s ability to evaluate glenohumeral instability and other motion related pathologies.