1. 1Department of Orthopedic Surgery, Keio University;
2. 2Department of Orthopaedic Surgery, Faculty of Medicine, University of Tokyo;
3. 3Department of Orthopaedic Surgery, Tokyo Medical and Dental University;
4. 4Department of Orthopaedic Surgery, Kudanzaka Hospital, Tokyo;
5. 5Departments of Spinal Reconstruction and
6. 6Orthopaedics, Hokkaido University Graduate School of Medicine, Sapporo;
7. 7Department of Orthopaedic Surgery, Dokkyo Medical University, Tochigi;
8. 8Department of Orthopaedic Surgery, School of Medicine, Kanazawa University, Kanazawa;
9. 9Department of Orthopaedic Surgery, Nagoya University Graduate School of Medicine, Nagoya;
10. 10Department of Orthopaedic Surgery, Hamamatsu University School of Medicine, Shizouka; and
11. 11Department of Orthopaedic Surgery, Chiba University Graduate School of Medicine, Chiba, Japan