Musculoskeletal model-based control strategy of an over-actuated glenohumeral simulator to assess joint biomechanics

Abstract

Abstract Determining the acting shoulder and muscle forces in vivo is very complex. In this study, we developed a control strategy for a glenohumeral simulator for ex vivo experiments that can mimic physiological glenohumeral motion and overcome the problem of over-actuation. The system includes ten muscle portions actuated via cables to induce upper arm motion in three degrees of freedom, including scapula rotation. A real-time optimizer was implemented to handle the over-actuation of the glenohumeral joint while ensuring a minimum of muscle tension. The functionality of the real-time optimizer was also used to simulate different extents of rotator cuff tears. Joint reaction forces were consistent with in vivo measurements. These results demonstrate the feasibility and added value of implementing a real-time optimizer for using in vivo data to drive a shoulder simulator.