Joint simulators are widely used to perform pre-(and post) clinical test of joint prostheses. Several experimental or commercial devices already exist for the hip and knee joints, but nothing is available yet for the shoulder joint. The first goal of this project is to extend an existing numerical model of the shoulder joint, in order to simulate an existing shoulder testing machine prototype. The second goal is to compare the model predictions (muscular and articular forces) with the machine measurements. And finally, the last goal is to use this comparative analysis to propose improvements of the model, or the machine, for an optimal correspondence with the physiological and clinical reality. This project will be done in collaboration with a prostheses manufacturer, Tornier (www.tornier.com), which developed the existing prototype.