1. Department of Orthopedic Surgery, Keio University School of Medicine, Tokyo, Japan
2. Keio Spine Research Group (KSRG), Tokyo, Japan
3. Department of Orthopedic Surgery, Keiyu Orthopedic Hospital, Tatebayashi, Japan
4. Department of Orthopedic Surgery, Japan Red Cross Shizuoka Hospital, Shizuoka, Japan
5. Department of Orthopedic Surgery, National Hospital Organization Murayama Medical Center, Tokyo, Japan
6. Department of Orthopedic Surgery, Saitama Medical Center, Saitama, Japan
7. Department of Orthopedic Surgery, Tokyo Dental College Ichikawa General Hospital, Chiba, Japan
8. Spine and Spinal Cord Center, International University of Health and Welfare (IUHW) Mita Hospital, Tokyo, Japan
9. Department of Orthopedic Surgery, Subaru Health Insurance Society Ota Memorial Hospital, Ota, Japan
10. New Spine Clinic Tokyo, Tokyo, Japan
11. Department of Orthopedic Surgery, Kanagawa Prefectural Police Association Keiyu Hospital, Yokohama, Japan