Toshitaka Yoshii1, Takashi Hirai2, Akio Iwanami3, Narihito Nagoshi3, Kazuhiro Takeuchi4, Kanji Mori5, Tsuyoshi Yamada2, Shoji Seki6, Takashi Tsuji3, Kanehiro Fujiyoshi3, Mitsuru Furukawa3, Soraya Nishimura3, Kanichiro Wada7, Masao Koda8, Takeo Furuya8, Yukihiro Matsuyama9, Tomohiko Hasegawa9, Katsushi Takeshita10, Atsushi Kimura10, Masahiko Abematsu11, Hirotaka Haro12, Tetsuro Ohba12, Masahiko Watanabe13, Hiroyuki Katoh13, Kei Watanabe14, Hiroshi Ozawa15, Haruo Kanno16, Shiro Imagama17, Kei Ando17, Shunsuke Fujibayashi18, Morio Matsumoto3, Masaya Nakamura3, Masashi Yamazaki19, Atsushi Okawa2, Yoshiharu Kawaguchi6. 1. Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. Electronic address: yoshii.orth@tmd.ac.jp. 2. Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 3. Department of Orthopedic Surgery, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku Ward, Tokyo 160-8582, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 4. Department of Orthopedic Surgery, National Hospital Organization Okayama Medical Center, 1711-1 Tamasu, Okayama, Okayama 701-1154, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 5. Department of Orthopedic Surgery, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 6. Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, 2630 Sugitani, Toyama, Toyama 930-0194, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 7. Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, 53 Honcho, Hirosaki, Aomori 036-8203, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 8. Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chuo Ward, Chiba, Chiba 260-0856, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 9. Department of Orthopedic Surgery, Hamamatsu University School of Medicine, 1-20-1 Handayama, Hamamatsu, Shizuoka 431-3125, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 10. Department of Orthopedics, Jichi Medical University, 3311-1 Yakushiji, Shimotsuke, Tochigi 329-0498, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 11. Department of Orthopedic Surgery, Graduate School of Medicine and Dental Science, Kagoshima University, 8-35-1 Sakuragaoka, Kagoshima, Kagoshima 890-8520, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 12. Department of Orthopedic Surgery, University of Yamanashi, 1110 Shimokato, Chuo Ward, Yamanashi 409-3898, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 13. Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, 143 Shimokasuya, Isehara, Kanagawa 259-1143, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 14. Department of Orthopedic Surgery, Niigata University Medicine and Dental General Hospital, 1-754 Asahimachidori, Chuo Ward, Niigata, Niigata 951-8520, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 15. Department of Orthopaedic Surgery, Tohoku Medical and Pharmaceutical University, 1-12-1 Fukumuro Miyaginoku, Sendai 983-8512, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 16. Department of Orthopaedic Surgery, Tohoku University School of Medicine, 1-1 Seiryomachi, Aoba Ward, Sendai, Miyagi 980-8574, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 17. Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, 65 Tsurumaicho, Showa Ward, Nagoya, Aichi 466-0065, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 18. Department of Orthopedic Surgery, Graduate School of Medicine, Kyoto University, 54 Kawaharacho, Shogoin, Sakyo Ward, Kyoto, Kyoto 606-8507, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan. 19. Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, 2-1-1 Amakubo, Tsukuba, Ibaraki 305-8576, Japan; Japanese Multicenter Research Organization for Ossification of the Spinal Ligament, Japan.
Abstract
BACKGROUND: Previous studies have shown that patients with cervical ossification of the posterior longitudinal ligament (OPLL) often have co-existing ossification of the nuchal ligament (ONL). However, no studies have focused on ONL and its relevance to the severity of OPLL or ossification of other spinal ligaments, such as anterior longitudinal ligament (OALL), ligamentum flavum (OLF), and supraspinous/interspinous ligament (OSIL). METHODS: In this multicenter study, we investigated ossification of the spinal ligaments in the whole spine computed tomography (CT) images of 233 cervical OPLL patients. The severity of ossification was evaluated using ossification index for each spinal ligament, calculated as the sum of the level of ossification. We compared the severity of ossification in each spinal ligament between patients with ONL and those without ONL. Furthermore, we investigated how the number of segments, where ONL exists, affects the severity of ossification in each spinal ligament. RESULTS: One hundred thirty patients (55.8%) had co-existing ONL in the cervical OPLL patients included in this study. The ONL (+) group included more male and aged patients. The cervical ossification indexes of OPLL and OALL were higher in ONL (+) patients than in ONL (-) patients. The thoracolumbar ossification indexes of OALL and OSIL were also higher in ONL (+) patients. Logistic regression analysis revealed that age, gender and cervical OA-index were independent factors correlating to the existence of ONL. In the cervical spine, both the ossification indexes of OALL and OPLL increased as the levels of ONL increased. Similarly, in the thoracolumbar spine, both the ossification indexes of OALL and OSIL were increased as the levels of cervical ONL increased. In the multiple regression analysis, cervical OA-index and thoracolumbar OSI-index showed significant correlation with the number of ONL levels. CONCLUSIONS: Co-existence of ONL in cervical OPLL patients was associated with the severity of spinal hyperostosis especially in cervical OPLL, OALL, thoracolumbar OALL and OSIL.
BACKGROUND: Previous studies have shown that patients with cervical ossification of the posterior longitudinal ligament (OPLL) often have co-existing ossification of the nuchal ligament (ONL). However, no studies have focused on ONL and its relevance to the severity of OPLL or ossification of other spinal ligaments, such as anterior longitudinal ligament (OALL), ligamentum flavum (OLF), and supraspinous/interspinous ligament (OSIL). METHODS: In this multicenter study, we investigated ossification of the spinal ligaments in the whole spine computed tomography (CT) images of 233 cervical OPLLpatients. The severity of ossification was evaluated using ossification index for each spinal ligament, calculated as the sum of the level of ossification. We compared the severity of ossification in each spinal ligament between patients with ONL and those without ONL. Furthermore, we investigated how the number of segments, where ONL exists, affects the severity of ossification in each spinal ligament. RESULTS: One hundred thirty patients (55.8%) had co-existing ONL in the cervical OPLLpatients included in this study. The ONL (+) group included more male and aged patients. The cervical ossification indexes of OPLL and OALL were higher in ONL (+) patients than in ONL (-) patients. The thoracolumbar ossification indexes of OALL and OSIL were also higher in ONL (+) patients. Logistic regression analysis revealed that age, gender and cervical OA-index were independent factors correlating to the existence of ONL. In the cervical spine, both the ossification indexes of OALL and OPLL increased as the levels of ONL increased. Similarly, in the thoracolumbar spine, both the ossification indexes of OALL and OSIL were increased as the levels of cervical ONL increased. In the multiple regression analysis, cervical OA-index and thoracolumbar OSI-index showed significant correlation with the number of ONL levels. CONCLUSIONS: Co-existence of ONL in cervical OPLLpatients was associated with the severity of spinal hyperostosis especially in cervical OPLL, OALL, thoracolumbar OALL and OSIL.