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Nagoshi N, Yoshii T, Egawa S, Sakai K, Kusano K, Tsutsui S, Hirai T, Matsukura Y, Wada K, Katsumi K, Koda M, Kimura A, Furuya T, Sato Y, Maki S, Nishida N, Nagamoto Y, Oshima Y, Ando K, Nakashima H, Takahata M, Mori K, Nakajima H, Murata K, Miyagi M, Kaito T, Yamada K, Banno T, Kato S, Ohba T, Moridaira H, Fujibayashi S, Katoh H, Kanno H, Watanabe K, Taneichi H, Imagama S, Kawaguchi Y, Takeshita K, Nakamura M, Matsumoto M, Yamazaki M. Comparison of Surgical Outcomes of Anterior and Posterior Fusion Surgeries for K-line (-) Cervical Ossification of the Posterior Longitudinal Ligament: A Prospective Multicenter Study. Spine (Phila Pa 1976) 2023; 48:937-943. [PMID: 36940262 DOI: 10.1097/brs.0000000000004634] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Accepted: 03/09/2023] [Indexed: 03/22/2023]
Abstract
STUDY DESIGN A prospective multicenter study. OBJECTIVE The objective of this study is to compare the surgical outcomes of anterior and posterior fusion surgeries in patients with K-line (-) cervical ossification of the posterior longitudinal ligament (OPLL). SUMMARY OF BACKGROUND DATA Although laminoplasty is effective for patients with K-line (+) OPLL, fusion surgery is recommended for those with K-line (-) OPLL. However, whether the anterior or posterior approach is preferable for this pathology has not been effectively determined. MATERIALS AND METHODS A total of 478 patients with myelopathy due to cervical OPLL from 28 institutions were prospectively registered from 2014 to 2017 and followed up for two years. Of the 478 patients, 45 and 46 with K-line (-) underwent anterior and posterior fusion surgeries, respectively. After adjusting for confounders in baseline characteristics using a propensity score-matched analysis, 54 patients in both the anterior and posterior groups (27 patients each) were evaluated. Clinical outcomes were assessed using the cervical Japanese Orthopaedic Association and the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire. RESULTS Both approaches showed comparable neurological and functional recovery. The cervical range of motion was significantly restricted in the posterior group because of the large number of fused vertebrae compared with the anterior group. The incidence of surgical complications was comparable between the cohorts, but the posterior group demonstrated a higher frequency of segmental motor paralysis, whereas the anterior group more frequently reported postoperative dysphagia. CONCLUSIONS Clinical improvement was comparable between anterior and posterior fusion surgeries for patients with K-line (-) OPLL. The ideal surgical approach should be informed based on the balance between the surgeon's technical preference and the risk of complications.
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Affiliation(s)
- Narihito Nagoshi
- Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
| | - Toshitaka Yoshii
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Satoru Egawa
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kenichiro Sakai
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, Kawaguchishi, Saitama, Japan
| | - Kazuo Kusano
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Kudanzaka Hospital, Chiyadaku, Japan
| | - Shunji Tsutsui
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama, Japan
| | - Takashi Hirai
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yu Matsukura
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, Tokyo, Japan
| | - Kanichiro Wada
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Hirosaki University Graduate School of Medicine, Hirosaki, Aomori, Japan
| | - Keiichi Katsumi
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Niigata University Medical and Dental General Hospital, Niigata, Niigata, Japan
| | - Masao Koda
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
| | - Atsushi Kimura
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedics, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - Takeo Furuya
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Yasunori Sato
- Department of Preventive Medicine and Public Health, Keio University School of Medicine, Tokyo, Japan
| | - Satoshi Maki
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Chiba University Graduate School of Medicine, Chiba, Japan
| | - Norihiro Nishida
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Yamaguchi University Graduate School of Medicine, Ube City, Yamaguchi, Japan
| | - Yukitaka Nagamoto
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Osaka Rosai Hospital, Sakaishi, Osaka, Japan
| | - Yasushi Oshima
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Faculty of Medicine, The University of Tokyo, Bunkyo-ku, Tokyo, Japan
| | - Kei Ando
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Hiroaki Nakashima
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Masahiko Takahata
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Faculty of Medicine and Graduate School of Medicine, Hokkaido University, Sapporo, Japan
| | - Kanji Mori
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Shiga University of Medical Science, Seta, Otsu, Shiga, Japan
| | - Hideaki Nakajima
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedics and Rehabilitation Medicine, Faculty of Medical Sciences University of Fukui, Yoshida-gun, Fukui, Japan
| | - Kazuma Murata
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Tokyo Medical University, Shinjuku-ku, Tokyo, Japan
| | - Masayuki Miyagi
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Kitasato University, School of Medicine, Sagamiharashi, Kanagawa, Japan
| | - Takashi Kaito
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Graduate School of Medicine, Osaka University, Osaka, Japan
| | - Kei Yamada
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Kurume University School of Medicine, Kurume-shi, Fukuoka, Japan
| | - Tomohiro Banno
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka, Japan
| | - Satoshi Kato
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kanazawa University, Kanazawa, Japan
| | - Tetsuro Ohba
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, University of Yamanashi, Yamanashi, Japan
| | - Hiroshi Moridaira
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Shimotsuga-gun, Tochigi, Japan
| | - Shunsuke Fujibayashi
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Hiroyuki Katoh
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Surgical Science, Tokai University School of Medicine, Isehara, Kanagawa, Japan
| | - Haruo Kanno
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Tohoku University School of Medicine, Sendai, Miyagi, Japan; and Department of Orthopedic Surgery, Faculty of Medicine, University of Toyama, Toyama, Toyama, Japan
| | - Kota Watanabe
- Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
| | - Hiroshi Taneichi
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopaedic Surgery, Dokkyo Medical University School of Medicine, Shimotsuga-gun, Tochigi, Japan
| | - Shiro Imagama
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Nagoya University Graduate School of Medicine, Nagoya, Aichi, Japan
| | - Yoshiharu Kawaguchi
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
| | - Katsushi Takeshita
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedics, Jichi Medical University, Shimotsuke, Tochigi, Japan
| | - Masaya Nakamura
- Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
| | - Morio Matsumoto
- Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
| | - Masashi Yamazaki
- Japanese Multicenter Research Organization for Ossification of the Spinal Ligament
- Department of Orthopedic Surgery, Faculty of Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan
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Onuma H, Sakai K, Arai Y, Torigoe I, Tomori M, Sakaki K, Hirai T, Egawa S, Kobayashi Y, Okawa A, Yoshii T. Augmented Reality Support for Anterior Decompression and Fusion Using Floating Method for Cervical Ossification of the Posterior Longitudinal Ligament. J Clin Med 2023; 12:jcm12082898. [PMID: 37109235 PMCID: PMC10143834 DOI: 10.3390/jcm12082898] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 04/06/2023] [Accepted: 04/14/2023] [Indexed: 04/29/2023] Open
Abstract
Anterior decompression and fusion (ADF) using the floating method for cervical ossification of the posterior longitudinal ligament (OPLL) is an ideal surgical technique, but it has a specific risk of insufficient decompression caused by the impingement of residual ossification. Augmented reality (AR) support is a novel technology that enables the superimposition of images onto the view of a surgical field. AR technology was applied to ADF for cervical OPLL to facilitate intraoperative anatomical orientation and OPLL identification. In total, 14 patients with cervical OPLL underwent ADF with microscopic AR support. The outline of the OPLL and the bilateral vertebral arteries was marked after intraoperative CT, and the reconstructed 3D image data were transferred and linked to the microscope. The AR microscopic view enabled us to visualize the ossification outline, which could not be seen directly in the surgical field, and allowed sufficient decompression of the ossification. Neurological disturbances were improved in all patients. No cases of serious complications, such as major intraoperative bleeding or reoperation due to the postoperative impingement of the floating OPLL, were registered. To our knowledge, this is the first report of the introduction of microscopic AR into ADF using the floating method for cervical OPLL with favorable clinical results.
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Affiliation(s)
- Hiroaki Onuma
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Kenichiro Sakai
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Yoshiyasu Arai
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Ichiro Torigoe
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Masaki Tomori
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Kyohei Sakaki
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Takashi Hirai
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan
| | - Satoru Egawa
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan
| | - Yutaka Kobayashi
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchi-shi 332-8558, Japan
| | - Atsushi Okawa
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan
| | - Toshitaka Yoshii
- Department of Orthopedic Surgery, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo Ward, Tokyo 113-8519, Japan
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Sakaki K, Sakai K, Arai Y, Torigoe I, Tomori M, Hirai T, Onuma H, Kobayashi Y, Okawa A, Yoshii T. Prospective Comparative Study of Dysphagia after Subaxial Cervical Spine Surgery: Cervical Spondylotic Myelopathy and Posterior Longitudinal Ligament Ossification. J Clin Med 2023; 12:jcm12051774. [PMID: 36902561 PMCID: PMC10003155 DOI: 10.3390/jcm12051774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 02/19/2023] [Accepted: 02/21/2023] [Indexed: 02/25/2023] Open
Abstract
We prospectively investigated the postoperative dysphagia in cervical posterior longitudinal ligament ossification (C-OPLL) and cervical spondylotic myelopathy (CSM) to identify the risk factors of each disease and the incidence. A series of 55 cases with C-OPLL: 13 anterior decompression with fusion (ADF), 16 posterior decompression with fusion (PDF), and 26 laminoplasty (LAMP), and a series of 123 cases with CSM: 61 ADF, 5 PDF, and 57 LAMP, were included. Vertebral level, number of segments, approach, and with or without fusion, and pre and postoperative values of Bazaz dysphagia score, C2-7 lordotic angle (∠C2-7), cervical range of motion, O-C2 lordotic angle, cervical Japanese Orthopedic Association score, and visual analog scale for neck pain were investigated. New dysphagia was defined as an increase in the Bazaz dysphagia score by one grade or more than one year after surgery. New dysphagia occurred in 12 cases with C-OPLL; 6 with ADF (46.2%), 4 with PDF (25%), 2 with LAMP (7.7%), and in 19 cases with CSM; 15 with ADF (24.6%), 1 with PDF (20%), and 3 with LAMP (1.8%). There was no significant difference in the incidence between the two diseases. Multivariate analysis demonstrated that increased ∠C2-7 was a risk factor for both diseases.
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Affiliation(s)
- Kyohei Sakaki
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Kenichiro Sakai
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Yoshiyasu Arai
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Ichiro Torigoe
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Masaki Tomori
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Takashi Hirai
- Department of Orthopaedics, Graduate School, Tokyo Medical and Dental University, Tokyo 108-0075, Japan
| | - Hiroaki Onuma
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Yutaka Kobayashi
- Department of Orthopedic Surgery, Saiseikai Kawaguchi General Hospital, 5-11-5 Nishikawaguchi, Kawaguchishi 332-8558, Japan
| | - Atsushi Okawa
- Department of Orthopaedics, Graduate School, Tokyo Medical and Dental University, Tokyo 108-0075, Japan
| | - Toshitaka Yoshii
- Department of Orthopaedics, Graduate School, Tokyo Medical and Dental University, Tokyo 108-0075, Japan
- Correspondence: ; Tel.: +81-3-5803-5678
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Li N, Ma S, Duan F, Wei Y, He D, Nagoshi N, Watanabe K, Nakamura M, Matsumoto M, Jeon H, Lee JJ, Kim KN, Ha Y, Kwan K, Cheung AKP, Clark A. Are clinical outcomes affected by laminoplasty method and K-line in patients with cervical ossification of posterior longitudinal ligament? A multicenter study. J Orthop Surg Res 2022; 17:513. [PMID: 36434732 PMCID: PMC9700906 DOI: 10.1186/s13018-022-03407-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/14/2022] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Open-door laminoplasty (ODL) and French-door laminoplasty (FDL) are the main laminoplasty techniques used to treat cervical ossification of the posterior longitudinal ligament (C-OPLL). However, few studies have compared the outcomes of ODL and modified FDL (mFDL) for C-OPLL. We explored the differences in outcomes between ODL and mFDL for C-OPLL and analyzed the technical efficacy of each procedure in patients with K-line (+) or (-) C-OPLL. METHODS From January 2010 to December 2015, 202 patients with K-line (+) or (-) C-OPLL were retrospectively recruited from 4 institutions. Clinical outcomes were evaluated using the Japanese Orthopaedic Association (JOA) score, JOA score recovery rate, operative time, blood loss, and complications. Univariate analysis and binary logistic regression models were adjusted for confounding factors. RESULTS Two hundred patients (mFDL, n = 69; ODL, n = 131) with a median follow-up of 42 months (range 36-54 months) were included. The postoperative JOA score significantly improved in both groups (P < 0.05). After adjusting for confounding factors, there was a statistically significant difference in blood loss (≥ 300 mL) between the two groups (P = 0.005), but there was no significant difference in the postoperative JOA score (≥ 14) (P = 0.062), JOA score recovery rate (≥ 0.82) (P = 0.187), or operative time (≥ 90 min) (P = 0.925). C5 palsy tended to occur more often in the mFDL group, although the difference was not significant (P > 0.05). The stratified analysis of the K-line status showed more blood loss in K-line (+) patients who underwent mFDL, but there was no significant difference in the postoperative JOA score, JOA score recovery rate, or operative time between the ODL and mFDL groups. Additionally, there was no significant difference in blood loss, postoperative JOA score, JOA score recovery rate, or operative time among all patients with K-line (+) or (-) C-OPLL in both groups. CONCLUSIONS Both ODL and mFDL are effective for patients with C-OPLL. However, more blood loss tends to occur during mFDL. This study showed no significant difference in the operative time or incidence of complications between the two techniques. The efficacy of ODL and mFDL was not affected by the K-line status (+ or -) in patients with C-OPLL.
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Affiliation(s)
- Nan Li
- grid.11135.370000 0001 2256 9319Department of Spine Surgery, Beijing Jishuitan Hospital, The Fourth Medical College of Peking University, 31 Xinjiekou Dongjie, Xicheng District, Beijing, 100035 China
| | - Sai Ma
- grid.11135.370000 0001 2256 9319Department of Spine Surgery, Beijing Jishuitan Hospital, The Fourth Medical College of Peking University, 31 Xinjiekou Dongjie, Xicheng District, Beijing, 100035 China
| | - Fangfang Duan
- grid.11135.370000 0001 2256 9319Department of Spine Surgery, Beijing Jishuitan Hospital, The Fourth Medical College of Peking University, 31 Xinjiekou Dongjie, Xicheng District, Beijing, 100035 China
| | - Yi Wei
- grid.11135.370000 0001 2256 9319Department of Spine Surgery, Beijing Jishuitan Hospital, The Fourth Medical College of Peking University, 31 Xinjiekou Dongjie, Xicheng District, Beijing, 100035 China
| | - Da He
- grid.11135.370000 0001 2256 9319Department of Spine Surgery, Beijing Jishuitan Hospital, The Fourth Medical College of Peking University, 31 Xinjiekou Dongjie, Xicheng District, Beijing, 100035 China
| | - Narihito Nagoshi
- grid.26091.3c0000 0004 1936 9959Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Kota Watanabe
- grid.26091.3c0000 0004 1936 9959Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Masaya Nakamura
- grid.26091.3c0000 0004 1936 9959Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Morio Matsumoto
- grid.26091.3c0000 0004 1936 9959Department of Orthopaedic Surgery, Keio University School of Medicine, Tokyo, Japan
| | - Hyeongseok Jeon
- grid.15444.300000 0004 0470 5454Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - J. J. Lee
- grid.15444.300000 0004 0470 5454Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Republic of Korea ,grid.264381.a0000 0001 2181 989XDepartment of Neurosurgery, Kangbuk Samsung Hospital, Sungkyunkwan University College of Medicine, Seoul, Republic of Korea
| | - Keung-Nyun Kim
- grid.15444.300000 0004 0470 5454Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Republic of Korea
| | - Yoon Ha
- grid.15444.300000 0004 0470 5454Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Republic of Korea ,grid.49100.3c0000 0001 0742 4007POSTECH Biotech Center, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673 Republic of Korea
| | - Kenny Kwan
- grid.194645.b0000000121742757Department of Orthopaedics and Traumatology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - A. K. P. Cheung
- grid.194645.b0000000121742757Department of Orthopaedics and Traumatology, LKS Faculty of Medicine, The University of Hong Kong, Hong Kong, China
| | - Aaron Clark
- grid.266102.10000 0001 2297 6811Department of Neurological Surgery, University of California, San Francisco, CA USA
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