[1] Nagoya Univ, Grad Sch Med, Dept Orthoped Surg, Nagoya, Aichi, Japan
[2] Osaka Univ, Grad Sch Med, Dept Orthoped Surg, Osaka, Japan
[3] Saiseikai Kawaguchi Hosp, Dept Orthoped Surg, Kawaguchi, Saitama, Japan
[4] Kudanzaka Hosp, Dept Orthoped Surg, Tokyo, Japan
[5] Keio Univ, Sch Med, Dept Orthoped Surg, Tokyo, Japan
[6] Univ Fukui, Dept Orthoped Surg, Fukui, Japan
[7] Hirosaki Univ, Grad Sch Med, Dept Orthoped Surg, Aomori, Japan
[8] Jichi Med Univ, Dept Orthoped, Shimotsuke, Tochigi, Japan
[9] Kanazawa Univ, Dept Orthoped Surg, Kanazawa, Ishikawa, Japan
[10] Natl Hosp Org Okayama Med Ctr, Dept Orthoped Surg, Okayama, Japan
[11] Hokkaido Univ, Grad Sch Med, Dept Orthoped Surg, Sapporo, Hokkaido, Japan
[12] Univ Tsukuba, Dept Orthoped Surg, Tsukuba, Ibaraki, Japan
[13] Tokai Univ, Sch Med, Dept Orthoped Surg, Surg Sci, Tokyo, Japan
[14] Kyoto Univ, Grad Sch Med, Dept Orthoped Surg, Kyoto, Japan
[15] Chiba Univ, Grad Sch Med, Dept Orthoped Surg, Chiba, Japan
[16] Univ Toyama, Fac Med, Dept Orthoped Surg, Toyama, Japan
[17] Hamamatsu Univ Sch Med, Dept Orthoped Surg, Hamamatsu, Shizuoka, Japan
[18] Tokyo Med & Dent Univ, Dept Orthoped Surg, Tokyo, Japan
[19] Japanese Org Study Ossificat Spinal Ligament JOSL, Tokyo, Japan