1. Department of Orthopaedic Surgery, Eastern Chiba Medical Center
2. Department of Orthopaedic Surgery, Sainou Hospital
3. Department of Orthopaedic Surgery, Funabashi Orthopaedic Hospital
4. Department of Orthopaedic Surgery, Chiba Rosai Hospital
5. Department of Orthopaedic Surgery, Kashiwa Municipal Hospital
6. Department of Orthopaedic Surgery, Japanese Red Cross Narita Hospital
7. Department of Orthopaedic Surgery, Matsudo Orthopaedic Hospital
8. Department of Orthopaedic Surgery, Funabashi Central Hospital
9. Department of Orthopaedic Surgery, University of Tsukuba
10. Department of Orthopaedic Surgery, Toho University of Sakura Hospital
11. Department of Orthopaedic Surgery, Kimitsu Chou Hospital
12. Department of Orthopaedic Surgery, Sanmu Medical Center
13. Department of Orthopaedic Surgery, Graduate School of Medicine, Chiba University
14. Department of Orthopaedic Surgery, Matsudo City General Hospital
15. Biostatistics Section, Clinical Research Center, Chiba University Hospital