1. Department of Neurosurgery, Hamburg University Medical Center, Martinistrasse 52, 20246 Hamburg, Germany
2. Department of Neurosurgery, Friedrich-Ebert-Krankenhaus, Friesenstr. 11, 24534 Neumünster, Germany
3. Department of Trauma and Orthopedic Surgery, Hamburg University Medical Center, Martinistrasse 52, 20246 Hamburg, Germany
4. Department of Spine and Neurosurgery, Tabea Krankenhaus Hamburg, Kösterbergstraße 32, 22587 Hamburg, Germany
5. Wirbelwerk Hamburg, Orchideenstieg 12, 22297 Hamburg, Germany
6. Department of Spinal Surgery, Hospital zum Heiligen Geist, Von-Broichhausen-Allee 1, 47906 Kempen, Germany
7. Department of Spine and Scoliosis Surgery, Lubinus Clinicum, Steenbeker Weg 25, 24106 Kiel, Germany
8. Department of Spine, Orthopädische Klinik Markgröningen, Kurt-Lindemann-Weg 10, 71706 Markgröningen, Germany