[1] Niigata Cent Hosp, Dept Orthoped Surg, Spine Ctr, Chuo Ku, 1-18 Shinkocho, Niigata, Niigata 9508556, Japan
[2] Niigata Univ, Dept Orthoped Surg, Med & Dent Gen Hosp, Chuo Ku, 1-757 Asahimachidori, Niigata, Niigata 9518510, Japan
[3] Tokyo Med & Dent Univ, Dept Orthoped Surg, Bunkyo Ku, 1-5-45 Yushima, Tokyo 1138519, Japan
[4] Chiba Univ, Grad Sch Med, Dept Orthopaed Surg, Chuo Ku, 1-8-1 Inohana, Chiba, Chiba 2600856, Japan
[5] Shiga Univ Med Sci, Dept Orthopaed Surg, Otsu, Shiga 5202192, Japan
[6] Keio Univ, Sch Med, Dept Orthopaed Surg, Shinjuku Ku, 35 Shinanomachi, Tokyo, Japan
[7] Natl Hosp Org Okayama Med Ctr, Dept Orthoped Surg, 1711-1 Tamasu, Okayama, Okayama, Japan
[8] Yamaguchi Univ, Dept Orthopaed Surg, Grad Sch Med, 1-1-1 Minamikogushi, Ube, Yamaguchi 7558505, Japan
[9] Osaka Univ, Dept Orthopaed Surg, Grad Sch Med, 2-2 Yamadaoka, Suita, Osaka 5650871, Japan
[10] Kanazawa Univ, Grad Sch Med Sci, Dept Orthoped Surg, 13-1 Takaramachi, Kanazawa, Ishikawa 9208641, Japan
[11] Univ Tsukuba, Dept Orthopaed Surg, Fac Med, 2-1-1 Amakubo, Tsukuba, Ibaraki 3058576, Japan
[12] Nagoya Univ, Grad Sch Med, Dept Orthoped Surg, Showa Ku, 65 Tsurumaicho, Nagoya, Aichi 4660065, Japan
[13] Tokyo Med Univ, Dept Orthoped Surg, Shinjuku Ku, 6-7-1 Nishishinjuku, Tokyo 1600023, Japan
[14] Hirosaki Univ, Dept Orthopaed Surg, Grad Sch Med, 53 Honcho, Hirosaki, Aomori 0368203, Japan
[15] Jichi Med Univ, Dept Orthopaed Surg, 3311-1 Yakushiji, Shimotsuke, Tochigi 3290498, Japan
[16] Univ Yamanashi, Dept Orthoped Surg, Chuo Ku, 1110 Shimokato, Yamanashi 4093898, Japan
[17] Tokai Univ, Dept Orthopaed Surg, Surg Sci, Sch Med, 143 Shimokasuya, Isehara, Kanagawa 2591143, Japan
[18] Hamamatsu Univ Sch Med, Dept Orthoped Surg, 1-20-1 Handayama, Hamamatsu, Shizuoka 4313125, Japan
[19] Tohoku Med & Pharmaceut Univ, Dept Orthopaed Surg, Miyagino Ku, 1-12-1 Fukumuro, Sendai, Miyagi 9838512, Japan
[20] Toyama Univ, Dept Orthoped Surg, Fac Med, 2630 Sugitani, Toyama, Toyama 9300194, Japan
[21] Japanese Org Study Ossificat Spinal Ligament JOSL, Tokyo, Japan