1. Department of Neurosurgery, Hospital Clínico Regional de Concepción, Concepción, Chile
2. Faculty of Medicine, University of Concepción, Concepción, Chile
3. Department of Neurosurgery, BG Klinikum Bergmannstrost Halle, Halle, Germany
4. Department of Orthopaedic Surgery, Menoufia University Faculty of Medicine, Shebin El-Kom, Menoufia, Egypt
5. Spinal Unit (UVM). Department of Orthopaedics, Centro Hospitalar Universitário de Santo António; ICBAS - School of Medical and Biomedical Sciences; Hospital CUF Trindade, Porto, Portugal
6. Research Department, AO Spine, AO Foundation, Davos, Switzerland
7. Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, MN, USA
8. Gerling Institute, Brooklyn, NY, USA
9. Department of Orthopedic Surgery, NYU Grossman School of Medicine, New York, NY, USA
10. Department of Orthopaedic Surgery, Keck School of Medicine, University of Southern California, Los Angeles, CA, USA