1. University of Toronto, Toronto, ON, Canada
2. Department of Neurosurgery, University of Maryland Medical System, Baltimore, MD, USA
3. Division of Neurosurgery, Department of Clinical Neurosciences, University of Cambridge, Cambridge UK
4. University of California San Francisco, San Francisco, CA, USA
5. Department of Surgery, University of Calgary, Calgary, AB, USA
6. University Health Network, Toronto, ON, Canada
7. Department of Neurosurgery, Oxford University Hospitals NHS Foundation Trust, Oxford, UK
8. Thomas Jefferson University, Philadelphia, NJ, USA
9. Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
10. Yonsei University, Seodaemun-gu, Korea
11. Department of Neurological Surgery, Thomas Jefferson University, Philadelphia, PA, USA
12. University of Washington, Seattle, WA, USA
13. Department of Orthopaedics and Traumatology, University of Hong Kong, Hong Kong
14. Department of Neurosurgery, Medical College of Wisconsin, Milwaukee, WI, USA
15. Houston Methodist Orthopedics & Sports Medicine Texas Medical Center, Houston, TX, USA
16. Department of Neurological Surgery, University of California Davis, Sacramento, CA, USA
17. Department of Orthopaedics, Keio University School of Medicine Graduate School of Medicine, Tokyo, Japan
18. Department of Neurosurgery, Hopitaux Universitaires de Geneve, Genève, Switzerland
19. Tehran University of Medical Sciences, Tehran, Iran
20. Department of Orthopaedics, Centro Hospitalar Universitario do Porto EPE, Porto, Portugal
21. Department of Neurosurgery, Amsterdam UMC VUMC Site, Amsterdam, Netherlands
22. New York University Medical Center, New York, NY, USA
23. Department of Orthopaedics, The University of British Columbia, Vancouver, BC, USA
24. Department of Surgery, St Michael's Hospital, Toronto, ON, USA