1. Department of Orthopaedic Surgery, The Rothman Institute at Thomas Jefferson University, Philadelphia, Pennsylvania, United States
2. Department of Orthopaedic Surgery, Catholic University, Curitiba, Brazil
3. Department of Neurosurgery, University of Maryland School of Medicine, Baltimore, Maryland, United States
4. Department of Orthopaedic Surgery, Ganga Hospital, Coimbatore, Tamil Nadu, India
5. Department of Orthopaedic Surgery, University of Washington, Seattle, Washington, United States
6. Department of Orthopaedic Surgery, The Swedish Neuroscience Institute, Seattle, Washington, United States
7. Center for Spinal Surgery and Neurotraumatology, Berufsgenossenschaftliche Unfallklinik Frankfurt, Frankfurt/Main, Germany
8. Center for Spinal Surgery, Schön Klinik Nürnberg Fürth, Fürth, Germany
9. Department of Orthopaedic Surgery, University of British Columbia, Vancouver, British Columbia, Canada
10. Department of Orthopaedic Surgery, Medical University Innsbruck, Innsbruck, Austria
11. Department of Orthopaedic Surgery, University Medical Center, Utrecht, The Netherlands