This study evaluated mid-term functional results of the Grammont inverted prosthesis for the treatment of shoulder osteoarthritis associated with massive cuff rupture. Twenty-eight patients with a minimum of 6 years of follow-up were evaluated. Clinical evaluation was performed on all patients preoperatively and at follow-up using the Constant score. Radiologic assessment included radiographs and magnetic resonance imaging preoperatively and radiographs at follow-up. Constant score improved from 27.4 preoperatively to 64.6 postoperatively. The inverted prosthesis is attractive and remains one of the options for treating cuff tear arthropathy. However, glenoid loosening remains a serious problem.