1. Department of Orthopedic Surgery and Spinal Surgery, the University of Tokyo Hospital, Tokyo, Japan
2. Department of Orthopedic Surgery, Japan Organization of Occupational Health and Safety Kanto Rosai Hospital, Kanagawa, Japan
3. Department of Information and Computer Technology, Faculty of Engineering, Tokyo University of Science, Tokyo, Japan
4. Department of Orthopedic Surgery, Tokyo Metropolitan Geriatric Hospital and Institute of Gerontology, Tokyo, Japan
5. Department of Orthopedic Surgery, Tokyo Metropolitan Hiroo Hospital, Tokyo, Japan
6. Department of Orthopedic Surgery, Tokyo Metropolitan Tama Medical Center, Tokyo, Japan
7. Department of Orthopedic Surgery, Tokyo Metropolitan Cancer and Infectious Diseases Center Komagome Hospital, Tokyo, Japan
8. Department of Medical Research and Management for Musculoskeletal Pain, 22nd Century Medical and Research Center, Faculty of Medicine, The University of Tokyo, Tokyo, Bunkyo-ku, Japan
9. for the OSSI investigators