Comparison Between Exactech Guided Personalized Surgery (GPS) and Conventional Instrumentation of Shoulder Arthroplasty

Inclusion Criteria: * Patient is at least 21 years of age at the time of surgery * Patient is indicated for reverse shoulder arthroplasty * Patient is willing to participate by complying with pre- and postoperative visit requirements * Patient is willing to participate for the entire length of the prescribed follow-up (minimum 2 years) * Patient is willing and able to review and sign a study informed consent form * Preop CT scan is within 3 months of the date of surgery Exclusion Criteria: * Revision shoulder arthroplasty * Reverse shoulder arthroplasty for fracture * Need for structural glenoid bone graft * Osteomyelitis of the proximal humerus or scapula; if a systemic infection or a secondary remote infection is suspected or confirmed, implantation should be delayed until infection is resolved * Inadequate or malformed bone that precludes adequate support or fixation of the prosthesis * Neuromuscular disorders that do not allow control of the joint * Significant injury to the brachial plexus * Non-functional deltoid muscles * The patient is unwilling or unable to comply with the post-operative care instructions * Patients who are a known drug or alcohol abuser, or have a psychological disorder (e.g. schizophrenia major depression, bipolar disorder, etc.) as defined by the DSM4 that affect follow-up care or treatment outcomes. * Alcohol, drug, or other subtance abuse * Any disease state that could adversaly affect the function or longevity of the implant * Patient is pregnant * Patient is a prisoner * Patient who are currently involved in any personal injury litigation, medical-legal or worker's compensation claims