1. Valladolid University Hospital, Royal Academy of Medicine and Surgery, 47008 Valladolid, Spain
2. Department of Orthopedic Surgery, Spine Unit, HFR Fribourg-Cantonal Hospital, 1708 Fribourg, Switzerland
3. Department of Orthopedics, Toulouse Lautrec Clinic, 81030 Albi, France
4. Department of Neurosurgery, A.R.N.A.S. Civico Di Cristina Benfratelli, 90127 Palermo, Italy
5. Department of Orthopedic Surgery, University Hospital of Rouen, 76031 Rouen, France
6. Department of Orthopedic Surgery, Hospital Beaujon, 92110 Clichy, France
7. Department of Trauma and Orthopedic Surgery, Südostbayern AG Clinic, Traunstein Clinic, 83278 Traunstein, Germany
8. Department of Spine Surgery, Loretto Hospital, 79100 Freiburg, Germany
9. LKH-Univ. Klinikum Graz, 8036 Graz, Austria
10. Department of Neurosurgery, Clinic of Cèdres, 31700 Cornebarrieu, France
11. Department of Neuroradiology, Regional University Hospital, 14033 Caen, France
12. Department of Traumatology and Orthopedic Surgery, University Hospital Principe De Asturias, 28805 Madrid, Spain
13. Department of Radiology, Bois-Cerf Clinic, 1006 Lausanne, Switzerland
14. Department of Neurosurgery Spine, Private Hospital Sévigné, 35567 Cesson-Sévigné, France
15. Department of Trauma and Reconstructive Surgery, Philipps University of Marburg, University Hospital of Giessen and Marburg, 35043 Marburg, Germany