1. Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
2. Department of Surgery, Division of Public Health Sciences, Washington University School of Medicine, St. Louis, Missouri, USA
3. Department of Neurological Surgery, Washington University School of Medicine, St. Louis, Missouri, USA
4. Department of Orthopaedic Surgery, Hospital for Special Surgery, New York, New York, USA