The Shoulder Service at Western Orthopaedics, lead by Dr. Hatzidakis and Dr. Sears, are collaborating with national leaders on two multi center clinical research trials. These investigations include collaborating with Case Western University in Cleveland on the evaluation of the importance of Vitamin D level and osteoporosis in patients undergoing reverse total shoulder arthroplasty. The other investigation involves collaboration with Rush University in Chicago and Duke University in North Carolina on the importance of physical therapy after reverse total shoulder arthroplasty. Patients are currently being enrolled in both clinical investigations