When rotator cuff deficiency is present with gleno-humeral osteoarthritis, the current treatment is a reverse total shoulder arthroplasty. The reverse shoulder prosthesis has inverted articular surfaces: a metallic ball (glenosphere) is fixed on the scapula side, usually by means of a metallic base plate, screwed within the glenoid bone, and a polyethylene cup is inserted within a metallic humeral component. Although the clinical outcome is rather satisfactory, at least for elderly people, the optimal fixation of the base plate remains open. The goal of this project is to test the hypothesis that a new base plate prototype could improve the mechanical stability and the surgical technique, compared to a classical existing one. The ASTM F2028 testing protocol will be used to evaluate the prototypes vs. the classical designs. Measurement will be done on cadaveric scapulae.