1. Department of Orthopaedic Surgery and Rehabilitation Medicine, The University of Chicago Hospitals, 5841 South Maryland Avenue, MC 3079, Chicago, IL 60637, USA
2. Department of Orthopaedic Surgery, Wake Forest University Baptist Medical Center, Medical Center Boulevard, P.O. Box 1070, Winston-Salem, NC 27157-1070, USA
3. Division of Shoulder Surgery, Massachusetts General Hospital, Yawkey Center 3G, 55 Fruit Street, Boston, MA 02114, USA