1. The George Washington University, School of Medicine and Health Services, Washington, District of Columbia, USA
2. Rush University Medical Center, Department of Orthopaedic Surgery, Chicago, Illinois, USA
3. William Beaumont Army Medical Center/Texas Tech University Health Sciences Center, Department of Orthopaedic Surgery, El Paso, Texas, USA
4. Carthage Area Hospital/Claxton-Hepburn Medical Center, Department of Orthopaedic Surgery, Carthage, New York, USA