1. 1Victor Horsley Department of Neurosurgery, The National Hospital for Neurology and Neurosurgery, London, United Kingdom;
2. 2Départment de Chirurgie Orthopédique et Traumatologique, L'Institute Mutualiste Monstsouris, Paris, France;
3. 3Department of Orthopaedics and Traumatology, Ospedale Maggiore, Bologna, Italy;
4. 4Department of Orthopedics, Aarhus University Hospital, Aarhus, Denmark;
5. 5Department of Orthopedics and Traumatology, Center for Spinal Surgery, Klinikum Karlsbad-Langensteinbach, Karlsbad, Germany; and
6. 6Department of Orthopedic Surgery, School of Medicine, Kanazawa University, Kanazawa, Japan