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