1. Department of Orthopaedic Surgery, St. Marianna University School of Medicine, Kawasaki, Kanagawa, Japan
2. Kanagawa Spine Research Society, Isehara, Kanagawa, Japan
3. Department of Orthopaedic Surgery, Kitasato University School of Medicine, Sagamihara, Kanagawa, Japan
4. Department of Orthopaedic Surgery, Tokai University School of Medicine, Isehara, Kanagawa, Japan
5. Department of Orthopaedic Surgery, St. Marianna University Yokohama Seibu Hospital, Yokohama, Kanagawa, Japan
6. Department of Orthopaedic Surgery, Tokai University Oiso Hospital, Oiso, Kanagawa, Japan
7. Department of Orthopaedic Surgery, Showa University Northern Yokohama Hospital, Yokohama, Kanagawa, Japan