1. Department of Orthopaedics and Sports Medicine, University of Washington Medical Center, 4245 Roosevelt Way N.E., Box 354740, Seattle, WA 98105, USA
2. Duke University School of Medicine, DUMC 2927, Durham, NC 27710, USA
3. Department of Orthopaedic Surgery, University of Rochester Medical Center, 601 Elmwood Avenue, Box 665, Rochester, NY 14642, USA