Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study

Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study Gan Jiang, Yi-li Xu, Ze-zhang Zhu, Yang Yu, Bin Wang, Yong Qiu, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8510413/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted 7 You are reading this latest preprint version Abstract Background Both ossification of the posterior longitudinal ligament (OPLL) and diffuse idiopathic skeletal hyperostosis (DISH) are characterized by abnormal calcification of the ligaments surrounding the spine and can be observed simultaneously in one patient. However, the association between cervical DISH and cevical OPLL has not been comprehensively investigated. This study aimed to investigate the influence of c-DISH on the progression of c-OPLL and to evaluate the clinical outcomes in patients with both c-DISH and c-OPLL. Methods A total of 192 patients with c-OPLL were enrolled and divided into DISH(-) (n = 152) and DISH(+) (n = 40) groups on the basis of the presence or absence of c-DISH. C-OPLL severity was evaluated via the ossification index (OP index) and canal narrowing ratio (CNR) on CT images. The distribution characteristics were analyzed by c-OPLL type and ossification range, with a focus on the most affected segment. Radiographic measurements included the C2–7 lordosis angle (CL angle), C7 slope, and C2–7 sagittal vertical axis (CSVA). Clinical outcome was assessed via both JOA and VAS scores. Results Both the OP index and the CNR were significantly greater in the DISH(+) group than in the DISH(-) group (P < 0.01). Patients in the DISH(+) group had a greater proportion of continuous-type OPLL but lower segmental and local types than those in the DISH(-) group. Patients in the DISH(+) group also had a greater incidence of OPLL at the C2, C3, and C4 levels (P < 0.05). Maximal ossification most frequently affects the C3 level in DISH(+) patients, whereas it affects the C5 level in DISH(-) patients. Compared with DISH(-) patients, DISH(+) patients had significantly poorer clinical outcomes both preoperatively and at the last follow-up. A significant negative correlation was observed between the CNR and both preoperative JOA scores. Conclusion C-OPLL in patients with c-DISH tend to have a proximal cervical distribution, more extensive lesions, and more severe spinal canal occupation, leading to poor neurological function recovery. Diffuse idiopathic skeletal hyperostosis Ossification Posterior longitudinal ligament Cervical spondylotic myelopathy Imaging feature Figures Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 1. Introduction Ossification of the posterior longitudinal ligament (OPLL) is a well-known cause of cervical spondylotic myelopathy (CSM), with a significantly higher prevalence among Asian populations, where epidemiological studies report an incidence ranging from 1.0% to 2.3% 1–3 . Patients with severe cervical OPLL often experience symptomatic spinal cord compression, resulting in progressive neurological deficits 4 , 5 . Diffuse idiopathic skeletal hyperostosis (DISH), another ectopic ossification disease, primarily affects the anterior longitudinal ligament. Clinically, patients with cervical OPLL may present with concurrent cervical DISH. Fujimori et al. 6 reported a 36% coexistence rate of DISH among OPLL patients. Nishimura et al. 7 showed that nearly 40% of cervical OPLL cases were complicated by DISH, with DISH severity linked to spinal ligament ossification. However, the effect of c-DISH on c-OPLL has not been well studied. In our study, we reviewed c-OPLL patients from 2017–2022 and compared imaging features and clinical outcomes between those with c-DISH and those without c-DISH, with the purpose of assessing the relationship between c-OPLL and c-DISH. 2. Methods 2.1. Subjects This single-center, prospective, case‒control study enrolled patients who underwent cervical surgery for OPLL at our institution between January 2018 and November 2022. All participants had both preoperative and postoperative radiographs and CT scans available. The exclusion criteria included diagnoses such as ankylosing spondylitis, tumors, or spinal fractures, as well as a history of previous cervical spine surgery. Finally, 192 patients who met the above criteria were included. All these patients were further divided into DISH(+) and DISH(-) groups on the basis of the presence or absence of DISH (Fig. 1 ). DISH was diagnosed radiologically by the presence of ossification along the anterior aspects of more than four consecutive vertebrae, as seen on preoperative whole-spine X-rays and CT images. There were 40 patients (30 males and 10 females) diagnosed with both OPLL and DISH in the DISH(+) group, with an average age of 59.0 years, whereas 152 patients (100 males and 52 females) were diagnosed with only OPLL in the DISH(-) group, with an average age of 55.9 years. The study protocol was approved by our hospital’s ethics committee, eliminating the need for additional informed consent for this retrospective analysis. 2.2. CT Measurements Preoperative CT scans of the cervical spine were performed in all patients. Senior spine surgeons screened all CT films to confirm OPLL and DISH diagnoses via the PACS image system (version 5.0, GE Healthcare). The severity of cervical OPLL was evaluated via CT images by calculating the canal narrowing ratio (CNR), which measures the anteroposterior diameter of the most stenotic spinal canal and compares it to an adjacent nonstenotic level within the subaxial cervical spine (typically one level above or below the pathology), using the formula: CNR (%) = [1 − (stenotic level AP diameter/normal level AP diameter)] × 100. 2) The ossification of the posterior longitudinal ligament index (OP index) was calculated by summing the vertebral and disc levels associated with OPLL on CT images, as previously described 8 . Additionally, the range of ossification and the type of OPLL (continuous, segmental, mixed, or local) were assessed to describe the distribution characteristics. 9 2.3. Radiographic Measurements The parameters measured in the lateral cervical radiographs included the following: 1) C2–7 lordotic angle (CL angle): between lines parallel to the lower endplates of C2 and C7. 2) C7 slope: between the horizontal line and the upper endplate of C7. 3) C2-7 sagittal vertical axis (CSVA): the horizontal distance from the posterior superior corner of C2 to C7. Measurements were taken twice and averaged by senior spine surgeons via Surgimap Version 2.0 (NYU, USA). 2.4. Assessment of pain and neurological function In the initial cohort of 192 patients, a total of 81 patients who underwent posterior cervical surgery had at least 1 year of follow-up, including 20 DISH(+) patients and 61 DISH(-) patients (Fig. 1 ). All 81 patients were evaluated via the Japanese Orthopedic Association (JOA) score for neurological function and the visual analog scale (VAS) for pain, both preoperatively and at the last follow-up. 2.5. Data analysis SPSS Statistics (v26.0; IBM Corp, Armonk, NY, USA) was used for the analysis. The data are shown as the means ± SDs. The Shapiro‒Wilk test was used to assess data normality. Normally distributed variables, including age, body mass index (BMI), CNR and C7 slope, were compared with the independent t test, whereas skewed data (OP index, CL angle, CSVA, JOA score, VAS score) were compared with the Mann‒Whitney U test. The categorical data are presented as proportions (n, %) and were analyzed with the chi-square test. Correlation analysis was performed via Pearson‒Spearman correlation analysis. p < 0.05 was considered statistically significant. 3. Results There were no statistically significant differences in any of the baseline characteristics between the initial two groups. Compared with those in the DISH(-) group, both the CNR (59.3% vs. 45.07%, P < 0.001) and the OP index (6.80 vs. 4.44, P < 0.01) were significantly greater in the DISH(+) group. Continuous-type OPLL was more common in the DISH(+) group (45.0% [18/40] vs. 22.4% [34/152], P < 0.01), whereas segmental-type OPLL (7.5% [3/40] vs. 30.3% [46/152], P < 0.01) and localized-type OPLL (2.5% [1/40] vs. 17.1% [26/152], P = 0.018) appeared more often in the DISH(-) group (Table 1 ). Table 1 Comparison of preoperative imaging features between the two groups. DISH(+) group (n = 40) DISH(-) group (n = 152) P value Male 30(75.0) 100(65.8) 0.268 Age 59.0 ± 10.0 55.9 ± 8.6 0.059 BMI (kg/m 2 ) 23.3 ± 1.0 23.1 ± 1.2 0.359 Diabetes 13(32.5) 33(21.7) 0.155 OP-index 6.80 ± 2.58 4.44 ± 2.75 0.001 ** CNR (%) 59.3 ± 12.4 45.07 ± 14.4 0.001 ** Type of OPLL Continuous 18(45.0) 34(22.4) 0.004 ** Segmental 3(7.5) 46(30.3) 0.003 ** Mixed 18(45.0) 46(30.3) 0.094 Local 1(2.5) 26(17.1) 0.018 * The C5 level was the most frequently involved level of OPLL in both groups. Additionally, compared with the DISH(-) group, the DISH(+) group presented a significantly greater proportion of OPLL in the proximal cervical spine (C2–C4) (Fig. 2 ). The segment with maximal ossification was most frequently observed at C3 in the DISH(+) group, whereas it was at C5 in the DISH(-) group (Fig. 3 ). Among the 81 patients who underwent posterior cervical surgery with at least 1 year of follow-up, no statistically significant difference was observed in any of the baseline data between the two groups. Compared with DISH(-) patients, DISH(+) patients still had significantly greater CNR and OP-index (P < 0.05). Additionally, DISH(+) patients had a greater number of surgical segments (5.4 ± 0.5 vs. 5.0 ± 0.7, P = 0.010). The proportion of patients with C2 as the upper instrumented vertebra (UIV) was significantly greater in the DISH(+) group (35.0% [7/20] vs. 8.2% [5/61] P = 0.003). Both groups of patients predominantly underwent laminectomy and fusion, with no significant difference in the choice of surgical procedure. (Table 2 ) Table 2 Comparison of baseline characteristics and surgical parameters between the two groups DISH(+) group (n = 20) DISH(-) group (n = 61) P value Male 16(80.0) 45(73.8) 0.575 Age(year) 59.0 ± 10.7 55.6 ± 8.9 0.165 BMI(kg/m 2 ) 23.9 ± 1.6 24.4 ± 1.4 0.285 Diabetes 6(30.0) 17(27.9) 0.854 CNR (%) 59.1 ± 13.0 49.8 ± 13.0 0.011 * OP-index 6.9 ± 2.0 5.3 ± 2.7 0.021 * Surgical segment 5.4 ± 0.5 5.0 ± 0.7 0.010 * UIV at C2 7(35.0) 5(8.2) 0.003 * Procedure 0.216 Laminoplasty 2 15 Laminectomy & Fusion 18 46 The preoperative CSVA was significantly greater in the DISH(+) group (29.4 ± 16.7 mm vs. 21.8 ± 10.3 mm, P = 0.016), whereas the preoperative CL was significantly smaller (7.4 ± 6.0° vs. 12.4 ± 8.5°, P = 0.016) than in the DISH(-) group. No significant differences in the preoperative C7 slope or sagittal parameters at the last follow-up were observed between the groups (Table 3 ). Table 3 Comparison of radiographic parameters between the two groups DISH(+) group (n = 20) DISH(-) group (n = 61) P value Preoperative CL angle (°) 7.4 ± 6.0 12.4 ± 8.5 0.016 * CSVA (mm) 29.4 ± 16.7 21.8 ± 10.3 0.016 * C7 Slope (°) 24.0 ± 8.4 23.3 ± 8.0 0.722 The last follow-up CL angle (°) 7.4 ± 5.6 8.2 ± 7.2 0.640 CSVA (mm) 34.9 ± 15.0 30.2 ± 11.2 0.143 C7 Slope (°) 25.6 ± 8.2 24.7 ± 6.1 0.596 Compared with the DISH(-) group, the DISH(+) group demonstrated significantly worse neurological function, as reflected by lower JOA scores both preoperatively and at the last follow-up (P < 0.05). Similarly, neck pain was more severe in the DISH(+) group, with significantly higher VAS scores observed both preoperatively and at the last follow-up assessment (P < 0.05) (Table 4 ). Table 4 Comparison of scale scores between the two groups DISH(+) group (n = 20) DISH(-) group (n = 61) P value JOA score preoperative 10.4 ± 2.2 12.7 ± 1.6 0.001 ** The last follow-up 14.5 ± 1.9 15.8 ± 1.0 0.010 * VAS score preoperative 4.1 ± 2.0 2.7 ± 1.8 0.002 ** The last follow-up 3.2 ± 1.4 2.4 ± 1.2 0.013 * The preoperative JOA score was negatively correlated with the CNR among the 81 patients (r= -0.225, P = 0.044), whereas no significant associations were found with the other imaging parameters (p > 0.05) (Table 5 ). Table 5 Correlations between imaging parameters and preoperative JOA scores in all patients (n = 81) Correlation Coefficient (r) P value preoperative CL angle 0.093 0.408 preoperative CSVA (mm) -0.093 0.410 preoperative C7 Slope (°) -0.199 0.075 OP-index -0.149 0.184 CNR -0.225 0.044 * 4. Discussion 4.1. Imaging characteristics of patients with cervical OPLL with and without DISH Both DISH and OPLL involve spinal heterotopic ossification but differ in pathogenesis and clinical features. Clinically, most patients with cervical DISH are asymptomatic; however, whether c-DISH play a role in the severity of c-OPLL remains unclear. Tauchi et al 10 compared 8 OPLL patients with DISH and 41 without DISH(+) patients and reported that the DISH(+) group had a greater incidence of continuous/mixed-type OPLL, whereas the DISH(-) group mainly presented segmental-type OPLL. However, the limited number of DISH(+) cases (n = 8) calls for cautious interpretation of these findings. Our study compared the CT features of 152 OPLL patients with DISH and 40 without DISH. The results revealed that DISH(+) patients had more extensive ossification and a higher proportion of continuous-type OPLL, which was consistent with Ryoji’s study. Additionally, we found that the CNR was significantly greater in the DISH(+) group, suggesting that c-OPLL with c-DISH has greater transverse progression with more severe spinal cord compression (Table 1 ). These results indicate that c-DISH may not only accelerate the longitudinal extension of c-OPLL but also promote its transverse progression. However, the underlying mechanisms linking these 2 diseases remain unclear. Kosaka et al 11 reported higher TGF-β1 levels in the ligament cells of DISH patients than in those without ossification. Yonemori et al 12 also reported increased levels of TGF-β superfamily members and receptors in the ligament tissues of OPLL patients compared with controls through immunohistochemistry. We presumed that the overexpression of TGF-β in DISH might also accelerate the progression of OPLL in patients with both DISH and OPLL. Previous studies reported that OPLL was most frequently observed at the C4 and C5 levels 9 , 13 , 14 . Our study revealed that both groups presented the highest incidence at the C5 level, which is consistent with the findings of previous studies. Notably, patients in the DISH(+) group had a significantly greater incidence of OPLL in the proximal cervical spine (C2-C4) than those in the DISH(-) group (Fig. 2 ). Most previous studies reported that DISH was predominantly located in the distal cervical spine (C5-C7) 15 , 16 , where anterior vertebral bridging significantly reduces segmental mobility in this region. However, the underlying mechanisms linking these 2 diseases remain unclear. Similar characteristics of distribution were also observed in our study. The restricted mobility was present in the distal cervical spine leading to compensatory hypermobility of the proximal cervical spine. Over time, increased compensatory motion may accelerate cervical degeneration and promote ossification in the proximal cervical region, which may explain why the DISH(+) group demonstrated a greater propensity for ossification in the proximal cervical region, as well as more severe ossification overall. Clinically, these patients require longer-segment fixation, even extending to the C2 level. This viewpoint has also been confirmed in this study (Table 2 ). 4.2. Clinical outcomes in patients with cervical OPLL with and without DISH Hirai et al 17 compared preoperative JOA scores between OPLL patients with and without DISH and reported no significant differences between the two groups. However, their study lacked a comparison of the degree of spinal canal stenosis between the two groups. In our study, among 81 patients who underwent posterior cervical surgery with at least one year of follow-up, 20 patients with OPLL and DISH presented a higher CNR and worse neurological function than 61 patients with OPLL alone, both preoperatively and at the final follow-up. Furthermore, the CNR was negatively correlated with the preoperative JOA score, suggesting that more severe cervical canal stenosis in DISH(+) patients may lead to poorer spinal cord function. Although all patients experienced neurological improvement after cervical surgery, those in the DISH(+) group experienced less recovery than those in the c-OPLL alone group (Table 4 ). These results underscore the importance of early intervention in DISH(+) patients to prevent progressive ossification from compromising surgical outcomes. Our study revealed that c-OPLL patients with c-DISH had higher preoperative and follow-up VAS scores than those with c-OPLL alone. Li et al 18 linked neck pain with greater CSVA in patients with cervical kyphosis. Korkmaz et al 19 enrolled patients with neck pain and reported that a decreased CL angle was associated with increased pain. We observed that DISH(+) patients had significantly greater CSVA and smaller CL angles preoperatively than DISH(-) patients. Therefore, we suppose that the worse sagittal cervical alignment in DISH(+) patients may be responsible for their higher preoperative VAS scores. Although the postoperative sagittal parameters were similar between the two groups at the last follow-up, the DISH(+) group still reported more severe neck pain (Fig. 4 , 5 ). The cervical semispinal muscles attached to the C2 spinous process is crucial for maintaining normal alignment and function of the cervical spine. Kato et al 20 reported that preserving C2 spinous process-attached muscles during posterior cervical surgery may reduce postoperative axial pain. Among our patients, those in the DISH(+) group had a greater proportion of upper instrumented vertebrae at C2 than those in the DISH(-) group (Table 2 ). Furthermore, longer fusion segments may be associated with increased postoperative risks for axial pain after posterior cervical surgery in DISH(+) patients, which explains the greater severity of neck pain in these patients at follow-up. 5. Conclusion Our results showed that c-OPLL in patients with c-DISH tend to have a proximal cervical distribution, more extensive lesions, and severe spinal canal occupation, causing cord compression and resulting in significant neurological deficits. For these patients, OPLL progression should be closely monitored, and early surgical intervention should be performed when needed to improve prognosis. Declarations Ethics approval and consent to participate: The study protocol was approved by ethics committee of Nanjing Drum Tower Hospital, eliminating the need for additional informed consent for this retrospective analysis. The ethics approval number: 2024-JS-19. This study adhered to the Helsinki Declaration. Consent for publication: Not Applicable Availability of data and materials: Not Applicable Competing interests : The authors declare that they have no competing interests Funding: 2023 Special Fund for the Development of New Medical Technologies, Nanjing Drum Tower Hospital Authors' contributions ：(I) Conception and design: Jun Jiang; (II) Administrative support: Yong Qiu; (III) Provision of study materials or patients: Jun Jiang, Yang Yu, Bin Wang, Zezhang Zhu, Yong Qiu; (IV) Collection and assembly of data: Gan Jiang, Yili Xu; (V) Data analysis and interpretation: Gan Jiang, Yili Xu, Jun Jiang, Yang Yu, Bin Wang, Zezhang Zhu, Yong Qiu; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors. Acknowledgements: Not applicable Authors' information (optional): Gan Jiang and Yili Xu contributed equally to this work. Clinical trial number: Not applicable Data availability: Not applicable Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study References Singh NA, Shetty AP, Jakkepally S, Kumarasamy D, Kanna RM, Rajasekaran S. Ossification of Posterior Longitudinal Ligament in Cervical Spine and Its Association With Ossified Lesions in the Whole Spine: A Cross-Sectional Study of 2500 CT Scans. Global Spine Journal . 2023;13(1):122-132. doi:10.1177/2192568221993440 Boody BS, Lendner M, Vaccaro AR. Ossification of the posterior longitudinal ligament in the cervical spine: a review. International Orthopedics (SICOT) . 2019;43(4):797-805. doi:10.1007/s00264-018-4106-5 Saetia K, Cho D, Lee S, Kim DH, Kim SD. Ossification of the posterior longitudinal ligament: a review. 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Osteoporos Int . 2014;25(3):1089-1098. doi:10.1007/s00198-013-2489-0 Ahmed O, Ramachandran K, Patel Y, et al. Diffuse Idiopathic Skeletal Hyperostosis Prevalence, Characteristics, and Associated Comorbidities: A Cross-Sectional Study of 1815 Whole Spine CT Scans. Global Spine Journal . Published online October 26, 2022:219256822211368. doi:10.1177/21925682221136844 Nguyen TCT, Yahara Y, Yasuda T, et al. Morphological characteristics of DISH in patients with OPLL and its association with high-sensitivity CRP: inflammatory DISH. Rheumatology . 2022;61(10):3981-3988. doi:10.1093/rheumatology/keac051 Hirai T, Nishimura S, Yoshii T, et al. Associations between Clinical Findings and Severity of Diffuse Idiopathic Skeletal Hyperostosis in Patients with Ossification of the Posterior Longitudinal Ligament. JCM . 2021;10(18):4137. doi:10.3390/jcm10184137 Li J, Zhang D, Shen Y. Impact of cervical sagittal parameters on axial neck pain in patients with cervical kyphosis. J Orthop Surg Res . 2020;15(1):434. doi:10.1186/s13018-020-01909-x Korkmaz M, Ceylan CM, Korkmaz MD. Is cervical sagittal alignment associated with pain and disability in myofascial pain syndrome?: A cross-sectional study. Clinical Neurology and Neurosurgery . 2024;245:108458. doi:10.1016/j.clineuro.2024.108458 Kato M, Nakamura H, Konishi S, et al. Effect of Preserving Paraspinal Muscles on Postoperative Axial Pain in the Selective Cervical Laminoplasty: Spine . 2008;33(14):E455-E459. doi:10.1097/BRS.0b013e318178e607 Additional Declarations No competing interests reported. Cite Share Download PDF Status: Under Review Version 1 posted Reviews received at journal 20 Mar, 2026 Reviewers agreed at journal 24 Feb, 2026 Reviewers invited by journal 08 Jan, 2026 Editor assigned by journal 08 Jan, 2026 Editor invited by journal 08 Jan, 2026 Submission checks completed at journal 07 Jan, 2026 First submitted to journal 07 Jan, 2026 You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8510413","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":572645591,"identity":"07c98ca0-891d-4b75-a0d3-50b0d307d594","order_by":0,"name":"Gan Jiang","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital, Nanjing University","correspondingAuthor":false,"prefix":"","firstName":"Gan","middleName":"","lastName":"Jiang","suffix":""},{"id":572645593,"identity":"c8504a8e-ee4c-4b0d-8f0b-b34cd327e9ab","order_by":1,"name":"Yi-li Xu","email":"","orcid":"","institution":"Nanjing Drum Tower Hospital Clinical College of Nanjing 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Tower Hospital, Nanjing University","correspondingAuthor":true,"prefix":"","firstName":"Jun","middleName":"","lastName":"Jiang","suffix":""}],"badges":[],"createdAt":"2026-01-04 05:23:11","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8510413/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8510413/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":100387867,"identity":"a3433313-8be5-4079-9b3f-3c9caa013d64","added_by":"auto","created_at":"2026-01-16 11:16:38","extension":"docx","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":973839,"visible":true,"origin":"","legend":"","description":"","filename":"2026.docx","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/b88dea32cc7998cf8dd8d27f.docx"},{"id":100388183,"identity":"5967c234-1332-41f4-9b64-1d2c1599d484","added_by":"auto","created_at":"2026-01-16 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11:17:07","extension":"xml","order_by":13,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":80358,"visible":true,"origin":"","legend":"","description":"","filename":"72e2f2d730e3426db236c029e2f506a21structuring.xml","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/56d104b4869ee2306964aefa.xml"},{"id":100388157,"identity":"a7243473-8752-4fd2-a5d5-a1c8737fdae0","added_by":"auto","created_at":"2026-01-16 11:17:08","extension":"html","order_by":14,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":89422,"visible":true,"origin":"","legend":"","description":"","filename":"earlyproof.html","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/f882b56cfbf5e842f14024db.html"},{"id":100387850,"identity":"bc3e92c5-f74c-4f87-9703-97d596236ed2","added_by":"auto","created_at":"2026-01-16 11:16:34","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":28528,"visible":true,"origin":"","legend":"\u003cp\u003eFlow diagram of the two-stage selection process\u003c/p\u003e","description":"","filename":"floatimage1.png","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/52c2ea911f23f38b4feab300.png"},{"id":100388135,"identity":"5b95d5c1-e1dc-41fb-b7d0-68e6e11dcafd","added_by":"auto","created_at":"2026-01-16 11:17:07","extension":"jpeg","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":60986,"visible":true,"origin":"","legend":"\u003cp\u003eThe distribution of cervical OPLL in the two groups\u003c/p\u003e","description":"","filename":"floatimage2.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/7947cefdc46b64e0428ede6b.jpeg"},{"id":100387838,"identity":"b7d38b14-bb77-4267-adf0-73f4ec21b695","added_by":"auto","created_at":"2026-01-16 11:16:26","extension":"jpeg","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":50683,"visible":true,"origin":"","legend":"\u003cp\u003eThe distribution of segments with maximal ossification in the two groups\u003c/p\u003e","description":"","filename":"floatimage3.jpeg","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/f1bcbcd4fdeb3b29d31efb60.jpeg"},{"id":100387839,"identity":"d8433066-4a8c-45f1-9d9d-8bcf1b21eaff","added_by":"auto","created_at":"2026-01-16 11:16:27","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":446692,"visible":true,"origin":"","legend":"\u003cp\u003eA patient with continuous-type OPLL and c-DISH (a). The most severe ossification was at C3, with a CNR of 70.5% (b). The patient showed severe spinal cord compression and cervical malalignment preoperatively (c-d). The preoperative JOA and VAS scores were 11 and 4, respectively. After laminectomy and fusion from C2 to T2 (e), the JOA score improved to 14, and the VAS score increased to 5 at the last follow-up.\u003c/p\u003e","description":"","filename":"floatimage4.png","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/ce1262f7bd748c62cf7889b0.png"},{"id":100387869,"identity":"a17e49f8-c9bf-4907-aaef-8b9261347a91","added_by":"auto","created_at":"2026-01-16 11:16:39","extension":"png","order_by":5,"title":"Figure 5","display":"","copyAsset":false,"role":"figure","size":421449,"visible":true,"origin":"","legend":"\u003cp\u003eA patient with continuous-type OPLL (a). The most significant ossification segment was observed at the C5 level, with a CNR of 37.1% (b). This patient showed severe spinal cord compression but a normal cervical alignment preoperatively (c-d). The preoperative JOA and VAS scores were 12 and 3, respectively. After laminectomy and fusion from C3 to T1 (e), the JOA score improved to 16, and the VAS score remained the same at the last follow-up.\u003c/p\u003e","description":"","filename":"floatimage5.png","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/5ef479c63e3628bbb90835a9.png"},{"id":100545799,"identity":"f2482b58-2633-4345-894c-821872e4d03c","added_by":"auto","created_at":"2026-01-19 06:39:12","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":2048728,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8510413/v1/db87d08b-e226-45fc-8d81-20765005b0d3.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study","fulltext":[{"header":"1. Introduction","content":"\u003cp\u003eOssification of the posterior longitudinal ligament (OPLL) is a well-known cause of cervical spondylotic myelopathy (CSM), with a significantly higher prevalence among Asian populations, where epidemiological studies report an incidence ranging from 1.0% to 2.3%\u003csup\u003e1\u0026ndash;3\u003c/sup\u003e. Patients with severe cervical OPLL often experience symptomatic spinal cord compression, resulting in progressive neurological deficits\u003csup\u003e\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e,\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e\u003c/sup\u003e. Diffuse idiopathic skeletal hyperostosis (DISH), another ectopic ossification disease, primarily affects the anterior longitudinal ligament. Clinically, patients with cervical OPLL may present with concurrent cervical DISH. Fujimori et al.\u003csup\u003e6\u003c/sup\u003e reported a 36% coexistence rate of DISH among OPLL patients. Nishimura et al.\u003csup\u003e7\u003c/sup\u003e showed that nearly 40% of cervical OPLL cases were complicated by DISH, with DISH severity linked to spinal ligament ossification. However, the effect of c-DISH on c-OPLL has not been well studied. In our study, we reviewed c-OPLL patients from 2017\u0026ndash;2022 and compared imaging features and clinical outcomes between those with c-DISH and those without c-DISH, with the purpose of assessing the relationship between c-OPLL and c-DISH.\u003c/p\u003e"},{"header":"2. Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003e2.1. Subjects\u003c/h2\u003e \u003cp\u003eThis single-center, prospective, case‒control study enrolled patients who underwent cervical surgery for OPLL at our institution between January 2018 and November 2022. All participants had both preoperative and postoperative radiographs and CT scans available. The exclusion criteria included diagnoses such as ankylosing spondylitis, tumors, or spinal fractures, as well as a history of previous cervical spine surgery. Finally, 192 patients who met the above criteria were included. All these patients were further divided into DISH(+) and DISH(-) groups on the basis of the presence or absence of DISH (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). DISH was diagnosed radiologically by the presence of ossification along the anterior aspects of more than four consecutive vertebrae, as seen on preoperative whole-spine X-rays and CT images. There were 40 patients (30 males and 10 females) diagnosed with both OPLL and DISH in the DISH(+) group, with an average age of 59.0 years, whereas 152 patients (100 males and 52 females) were diagnosed with only OPLL in the DISH(-) group, with an average age of 55.9 years. The study protocol was approved by our hospital\u0026rsquo;s ethics committee, eliminating the need for additional informed consent for this retrospective analysis.\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec4\" class=\"Section2\"\u003e \u003ch2\u003e2.2. CT Measurements\u003c/h2\u003e \u003cp\u003ePreoperative CT scans of the cervical spine were performed in all patients. Senior spine surgeons screened all CT films to confirm OPLL and DISH diagnoses via the PACS image system (version 5.0, GE Healthcare). The severity of cervical OPLL was evaluated via CT images by calculating the canal narrowing ratio (CNR), which measures the anteroposterior diameter of the most stenotic spinal canal and compares it to an adjacent nonstenotic level within the subaxial cervical spine (typically one level above or below the pathology), using the formula: CNR (%) = [1 \u0026minus; (stenotic level AP diameter/normal level AP diameter)] \u0026times; 100. 2) The ossification of the posterior longitudinal ligament index (OP index) was calculated by summing the vertebral and disc levels associated with OPLL on CT images, as previously described\u003csup\u003e\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e\u003c/sup\u003e. Additionally, the range of ossification and the type of OPLL (continuous, segmental, mixed, or local) were assessed to describe the distribution characteristics. \u003csup\u003e9\u003c/sup\u003e\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003e2.3. Radiographic Measurements\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eThe parameters measured in the lateral cervical radiographs included the following: 1) C2\u0026ndash;7 lordotic angle (CL angle): between lines parallel to the lower endplates of C2 and C7. 2) C7 slope: between the horizontal line and the upper endplate of C7. 3) C2-7 sagittal vertical axis (CSVA): the horizontal distance from the posterior superior corner of C2 to C7. Measurements were taken twice and averaged by senior spine surgeons via Surgimap Version 2.0 (NYU, USA).\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec6\" class=\"Section2\"\u003e \u003ch2\u003e2.4. Assessment of pain and neurological function\u003c/h2\u003e \u003cp\u003e \u003cdiv class=\"BlockQuote\"\u003e \u003cp\u003eIn the initial cohort of 192 patients, a total of 81 patients who underwent posterior cervical surgery had at least 1 year of follow-up, including 20 DISH(+) patients and 61 DISH(-) patients (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). All 81 patients were evaluated via the Japanese Orthopedic Association (JOA) score for neurological function and the visual analog scale (VAS) for pain, both preoperatively and at the last follow-up.\u003c/p\u003e \u003c/div\u003e \u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec7\" class=\"Section2\"\u003e \u003ch2\u003e2.5. Data analysis\u003c/h2\u003e \u003cp\u003eSPSS Statistics (v26.0; IBM Corp, Armonk, NY, USA) was used for the analysis. The data are shown as the means\u0026thinsp;\u0026plusmn;\u0026thinsp;SDs. The Shapiro‒Wilk test was used to assess data normality. Normally distributed variables, including age, body mass index (BMI), CNR and C7 slope, were compared with the independent t test, whereas skewed data (OP index, CL angle, CSVA, JOA score, VAS score) were compared with the Mann‒Whitney U test. The categorical data are presented as proportions (n, %) and were analyzed with the chi-square test. Correlation analysis was performed via Pearson‒Spearman correlation analysis. p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"3. Results","content":"\u003cp\u003eThere were no statistically significant differences in any of the baseline characteristics between the initial two groups. Compared with those in the DISH(-) group, both the CNR (59.3% vs. 45.07%, P\u0026thinsp;\u0026lt;\u0026thinsp;0.001) and the OP index (6.80 vs. 4.44, P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) were significantly greater in the DISH(+) group. Continuous-type OPLL was more common in the DISH(+) group (45.0% [18/40] vs. 22.4% [34/152], P\u0026thinsp;\u0026lt;\u0026thinsp;0.01), whereas segmental-type OPLL (7.5% [3/40] vs. 30.3% [46/152], P\u0026thinsp;\u0026lt;\u0026thinsp;0.01) and localized-type OPLL (2.5% [1/40] vs. 17.1% [26/152], P\u0026thinsp;=\u0026thinsp;0.018) appeared more often in the DISH(-) group (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of preoperative imaging features between the two groups.\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDISH(+) group (n\u0026thinsp;=\u0026thinsp;40)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDISH(-) group (n\u0026thinsp;=\u0026thinsp;152)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003e\u003cem\u003eP\u003c/em\u003e value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e30(75.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e100(65.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.268\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e59.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e55.9\u0026thinsp;\u0026plusmn;\u0026thinsp;8.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.059\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI (kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e23.3\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e23.1\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.359\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e13(32.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e33(21.7)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.155\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOP-index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e6.80\u0026thinsp;\u0026plusmn;\u0026thinsp;2.58\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e4.44\u0026thinsp;\u0026plusmn;\u0026thinsp;2.75\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCNR (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e59.3\u0026thinsp;\u0026plusmn;\u0026thinsp;12.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e45.07\u0026thinsp;\u0026plusmn;\u0026thinsp;14.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eType of OPLL\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eContinuous\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18(45.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e34(22.4)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.004\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSegmental\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e3(7.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46(30.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMixed\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e18(45.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e46(30.3)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.094\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLocal\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e1(2.5)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e26(17.1)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.018\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe C5 level was the most frequently involved level of OPLL in both groups. Additionally, compared with the DISH(-) group, the DISH(+) group presented a significantly greater proportion of OPLL in the proximal cervical spine (C2\u0026ndash;C4) (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). The segment with maximal ossification was most frequently observed at C3 in the DISH(+) group, whereas it was at C5 in the DISH(-) group (Fig.\u0026nbsp;\u003cspan refid=\"Fig3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003eAmong the 81 patients who underwent posterior cervical surgery with at least 1 year of follow-up, no statistically significant difference was observed in any of the baseline data between the two groups. Compared with DISH(-) patients, DISH(+) patients still had significantly greater CNR and OP-index (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Additionally, DISH(+) patients had a greater number of surgical segments (5.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5 vs. 5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7, P\u0026thinsp;=\u0026thinsp;0.010). The proportion of patients with C2 as the upper instrumented vertebra (UIV) was significantly greater in the DISH(+) group (35.0% [7/20] vs. 8.2% [5/61] P\u0026thinsp;=\u0026thinsp;0.003). Both groups of patients predominantly underwent laminectomy and fusion, with no significant difference in the choice of surgical procedure. (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e)\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab2\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of baseline characteristics and surgical parameters between the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDISH(+) group (n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDISH(-) group (n\u0026thinsp;=\u0026thinsp;61)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eMale\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e16(80.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e45(73.8)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.575\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge(year)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.0\u0026thinsp;\u0026plusmn;\u0026thinsp;10.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e55.6\u0026thinsp;\u0026plusmn;\u0026thinsp;8.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.165\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBMI(kg/m\u003csup\u003e2\u003c/sup\u003e)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e23.9\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e24.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.285\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eDiabetes\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6(30.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e17(27.9)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.854\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCNR (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e59.1\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e49.8\u0026thinsp;\u0026plusmn;\u0026thinsp;13.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.011\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOP-index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e6.9\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.3\u0026thinsp;\u0026plusmn;\u0026thinsp;2.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.021\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eSurgical segment\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e5.4\u0026thinsp;\u0026plusmn;\u0026thinsp;0.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5.0\u0026thinsp;\u0026plusmn;\u0026thinsp;0.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.010\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eUIV at C2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e7(35.0)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e5(8.2)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.003\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eProcedure\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.216\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaminoplasty\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eLaminectomy \u0026amp; Fusion\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e18\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e46\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe preoperative CSVA was significantly greater in the DISH(+) group (29.4\u0026thinsp;\u0026plusmn;\u0026thinsp;16.7 mm vs. 21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3 mm, P\u0026thinsp;=\u0026thinsp;0.016), whereas the preoperative CL was significantly smaller (7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u0026deg; vs. 12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u0026deg;, P\u0026thinsp;=\u0026thinsp;0.016) than in the DISH(-) group. No significant differences in the preoperative C7 slope or sagittal parameters at the last follow-up were observed between the groups (Table\u0026nbsp;\u003cspan refid=\"Tab3\" class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab3\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of radiographic parameters between the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\"\u0026plusmn;\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDISH(+) group (n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDISH(-) group (n\u0026thinsp;=\u0026thinsp;61)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003ePreoperative\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCL angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;6.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e12.4\u0026thinsp;\u0026plusmn;\u0026thinsp;8.5\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.016\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSVA (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e29.4\u0026thinsp;\u0026plusmn;\u0026thinsp;16.7\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e21.8\u0026thinsp;\u0026plusmn;\u0026thinsp;10.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.016\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC7 Slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e24.0\u0026thinsp;\u0026plusmn;\u0026thinsp;8.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e23.3\u0026thinsp;\u0026plusmn;\u0026thinsp;8.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.722\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThe last follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e\u0026nbsp;\u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e\u0026nbsp;\u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCL angle (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e7.4\u0026thinsp;\u0026plusmn;\u0026thinsp;5.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e8.2\u0026thinsp;\u0026plusmn;\u0026thinsp;7.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.640\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCSVA (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e34.9\u0026thinsp;\u0026plusmn;\u0026thinsp;15.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e30.2\u0026thinsp;\u0026plusmn;\u0026thinsp;11.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.143\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eC7 Slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c2\"\u003e \u003cp\u003e25.6\u0026thinsp;\u0026plusmn;\u0026thinsp;8.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\"\u0026plusmn;\" colname=\"c3\"\u003e \u003cp\u003e24.7\u0026thinsp;\u0026plusmn;\u0026thinsp;6.1\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c4\"\u003e \u003cp\u003e0.596\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eCompared with the DISH(-) group, the DISH(+) group demonstrated significantly worse neurological function, as reflected by lower JOA scores both preoperatively and at the last follow-up (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Similarly, neck pain was more severe in the DISH(+) group, with significantly higher VAS scores observed both preoperatively and at the last follow-up assessment (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab4\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 4\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eComparison of scale scores between the two groups\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"4\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c4\" colnum=\"4\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eDISH(+) group (n\u0026thinsp;=\u0026thinsp;20)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eDISH(-) group (n\u0026thinsp;=\u0026thinsp;61)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c4\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eJOA score\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e10.4\u0026thinsp;\u0026plusmn;\u0026thinsp;2.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e12.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.6\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.001\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThe last follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e14.5\u0026thinsp;\u0026plusmn;\u0026thinsp;1.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e15.8\u0026thinsp;\u0026plusmn;\u0026thinsp;1.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.010\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"4\" nameend=\"c4\" namest=\"c1\"\u003e \u003cp\u003eVAS score\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e4.1\u0026thinsp;\u0026plusmn;\u0026thinsp;2.0\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.7\u0026thinsp;\u0026plusmn;\u0026thinsp;1.8\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.002\u003csup\u003e**\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eThe last follow-up\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e3.2\u0026thinsp;\u0026plusmn;\u0026thinsp;1.4\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e2.4\u0026thinsp;\u0026plusmn;\u0026thinsp;1.2\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c4\"\u003e \u003cp\u003e0.013\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003eThe preoperative JOA score was negatively correlated with the CNR among the 81 patients (r= -0.225, P\u0026thinsp;=\u0026thinsp;0.044), whereas no significant associations were found with the other imaging parameters (p\u0026thinsp;\u0026gt;\u0026thinsp;0.05) (Table\u0026nbsp;\u003cspan refid=\"Tab5\" class=\"InternalRef\"\u003e5\u003c/span\u003e).\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab5\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 5\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eCorrelations between imaging parameters and preoperative JOA scores in all patients (n\u0026thinsp;=\u0026thinsp;81)\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"char\" char=\".\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eCorrelation Coefficient (r)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eP value\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative CL angle\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e0.093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.408\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative CSVA (mm)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.093\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.410\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003epreoperative C7 Slope (\u0026deg;)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.199\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.075\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eOP-index\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.149\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.184\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eCNR\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c2\"\u003e \u003cp\u003e-0.225\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"char\" char=\".\" colname=\"c3\"\u003e \u003cp\u003e0.044\u003csup\u003e*\u003c/sup\u003e\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e \u003cp\u003e \u003c/p\u003e"},{"header":"4. Discussion","content":"\u003cdiv id=\"Sec10\" class=\"Section2\"\u003e \u003ch2\u003e4.1. Imaging characteristics of patients with cervical OPLL with and without DISH\u003c/h2\u003e \u003cp\u003eBoth DISH and OPLL involve spinal heterotopic ossification but differ in pathogenesis and clinical features. Clinically, most patients with cervical DISH are asymptomatic; however, whether c-DISH play a role in the severity of c-OPLL remains unclear. Tauchi et al\u003csup\u003e10\u003c/sup\u003e compared 8 OPLL patients with DISH and 41 without DISH(+) patients and reported that the DISH(+) group had a greater incidence of continuous/mixed-type OPLL, whereas the DISH(-) group mainly presented segmental-type OPLL. However, the limited number of DISH(+) cases (n\u0026thinsp;=\u0026thinsp;8) calls for cautious interpretation of these findings. Our study compared the CT features of 152 OPLL patients with DISH and 40 without DISH. The results revealed that DISH(+) patients had more extensive ossification and a higher proportion of continuous-type OPLL, which was consistent with Ryoji\u0026rsquo;s study. Additionally, we found that the CNR was significantly greater in the DISH(+) group, suggesting that c-OPLL with c-DISH has greater transverse progression with more severe spinal cord compression (Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e). These results indicate that c-DISH may not only accelerate the longitudinal extension of c-OPLL but also promote its transverse progression. However, the underlying mechanisms linking these 2 diseases remain unclear. Kosaka et al\u003csup\u003e11\u003c/sup\u003e reported higher TGF-β1 levels in the ligament cells of DISH patients than in those without ossification. Yonemori et al\u003csup\u003e12\u003c/sup\u003e also reported increased levels of TGF-β superfamily members and receptors in the ligament tissues of OPLL patients compared with controls through immunohistochemistry. We presumed that the overexpression of TGF-β in DISH might also accelerate the progression of OPLL in patients with both DISH and OPLL.\u003c/p\u003e \u003cp\u003ePrevious studies reported that OPLL was most frequently observed at the C4 and C5 levels\u003csup\u003e\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e,\u003cspan citationid=\"CR13\" class=\"CitationRef\"\u003e13\u003c/span\u003e,\u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e14\u003c/span\u003e\u003c/sup\u003e. Our study revealed that both groups presented the highest incidence at the C5 level, which is consistent with the findings of previous studies. Notably, patients in the DISH(+) group had a significantly greater incidence of OPLL in the proximal cervical spine (C2-C4) than those in the DISH(-) group (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Most previous studies reported that DISH was predominantly located in the distal cervical spine (C5-C7)\u003csup\u003e\u003cspan citationid=\"CR15\" class=\"CitationRef\"\u003e15\u003c/span\u003e,\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e\u003c/sup\u003e, where anterior vertebral bridging significantly reduces segmental mobility in this region. However, the underlying mechanisms linking these 2 diseases remain unclear. Similar characteristics of distribution were also observed in our study. The restricted mobility was present in the distal cervical spine leading to compensatory hypermobility of the proximal cervical spine. Over time, increased compensatory motion may accelerate cervical degeneration and promote ossification in the proximal cervical region, which may explain why the DISH(+) group demonstrated a greater propensity for ossification in the proximal cervical region, as well as more severe ossification overall. Clinically, these patients require longer-segment fixation, even extending to the C2 level. This viewpoint has also been confirmed in this study (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003c/div\u003e \u003cdiv id=\"Sec11\" class=\"Section2\"\u003e \u003ch2\u003e4.2. Clinical outcomes in patients with cervical OPLL with and without DISH\u003c/h2\u003e \u003cp\u003eHirai et al\u003csup\u003e17\u003c/sup\u003e compared preoperative JOA scores between OPLL patients with and without DISH and reported no significant differences between the two groups. However, their study lacked a comparison of the degree of spinal canal stenosis between the two groups. In our study, among 81 patients who underwent posterior cervical surgery with at least one year of follow-up, 20 patients with OPLL and DISH presented a higher CNR and worse neurological function than 61 patients with OPLL alone, both preoperatively and at the final follow-up. Furthermore, the CNR was negatively correlated with the preoperative JOA score, suggesting that more severe cervical canal stenosis in DISH(+) patients may lead to poorer spinal cord function. Although all patients experienced neurological improvement after cervical surgery, those in the DISH(+) group experienced less recovery than those in the c-OPLL alone group (Table\u0026nbsp;\u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003e4\u003c/span\u003e). These results underscore the importance of early intervention in DISH(+) patients to prevent progressive ossification from compromising surgical outcomes.\u003c/p\u003e \u003cp\u003eOur study revealed that c-OPLL patients with c-DISH had higher preoperative and follow-up VAS scores than those with c-OPLL alone. Li et al\u003csup\u003e18\u003c/sup\u003e linked neck pain with greater CSVA in patients with cervical kyphosis. Korkmaz et al\u003csup\u003e19\u003c/sup\u003e enrolled patients with neck pain and reported that a decreased CL angle was associated with increased pain. We observed that DISH(+) patients had significantly greater CSVA and smaller CL angles preoperatively than DISH(-) patients. Therefore, we suppose that the worse sagittal cervical alignment in DISH(+) patients may be responsible for their higher preoperative VAS scores.\u003c/p\u003e \u003cp\u003eAlthough the postoperative sagittal parameters were similar between the two groups at the last follow-up, the DISH(+) group still reported more severe neck pain (Fig.\u0026nbsp;\u003cspan refid=\"Fig4\" class=\"InternalRef\"\u003e4\u003c/span\u003e, \u003cspan refid=\"Fig5\" class=\"InternalRef\"\u003e5\u003c/span\u003e). The cervical semispinal muscles attached to the C2 spinous process is crucial for maintaining normal alignment and function of the cervical spine. Kato et al\u003csup\u003e20\u003c/sup\u003e reported that preserving C2 spinous process-attached muscles during posterior cervical surgery may reduce postoperative axial pain. Among our patients, those in the DISH(+) group had a greater proportion of upper instrumented vertebrae at C2 than those in the DISH(-) group (Table\u0026nbsp;\u003cspan refid=\"Tab2\" class=\"InternalRef\"\u003e2\u003c/span\u003e). Furthermore, longer fusion segments may be associated with increased postoperative risks for axial pain after posterior cervical surgery in DISH(+) patients, which explains the greater severity of neck pain in these patients at follow-up.\u003c/p\u003e \u003c/div\u003e"},{"header":"5. Conclusion","content":"\u003cp\u003eOur results showed that c-OPLL in patients with c-DISH tend to have a proximal cervical distribution, more extensive lesions, and severe spinal canal occupation, causing cord compression and resulting in significant neurological deficits. For these patients, OPLL progression should be closely monitored, and early surgical intervention should be performed when needed to improve prognosis.\u003c/p\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval and consent to participate:\u003c/strong\u003e The study protocol was approved by ethics committee of Nanjing Drum Tower Hospital, eliminating the need for additional informed consent for this retrospective analysis. The ethics approval number: 2024-JS-19. This study adhered to the Helsinki Declaration.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication: \u003c/strong\u003eNot Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials:\u003c/strong\u003e Not Applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e: The authors declare that they have no competing interests\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding: \u003c/strong\u003e2023 Special Fund for the Development of \u0026nbsp; New Medical Technologies, Nanjing Drum Tower Hospital\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; contributions\u003c/strong\u003e：(I) Conception and design: Jun Jiang; (II) Administrative support: Yong Qiu; (III) Provision of study materials or patients: Jun Jiang, Yang Yu, Bin Wang, Zezhang Zhu, Yong Qiu; (IV) Collection and assembly of data: Gan Jiang, Yili Xu; (V) Data analysis and interpretation: Gan Jiang, Yili Xu, Jun Jiang, Yang Yu, Bin Wang, Zezhang Zhu, Yong Qiu; (VI) Manuscript writing: All authors; (VII) Final approval of manuscript: All authors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements: \u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors\u0026apos; information (optional): \u003c/strong\u003eGan Jiang and Yili Xu contributed equally to this work.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eClinical trial number:\u003c/strong\u003e Not applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eData availability:\u0026nbsp;\u003c/strong\u003eNot applicable\u003c/p\u003e\n\u003cp\u003eComparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eSingh NA, Shetty AP, Jakkepally S, Kumarasamy D, Kanna RM, Rajasekaran S. Ossification of Posterior Longitudinal Ligament in Cervical Spine and Its Association With Ossified Lesions in the Whole Spine: A Cross-Sectional Study of 2500 CT Scans. \u003cem\u003eGlobal Spine Journal\u003c/em\u003e. 2023;13(1):122-132. doi:10.1177/2192568221993440\u003c/li\u003e\n\u003cli\u003eBoody BS, Lendner M, Vaccaro AR. Ossification of the posterior longitudinal ligament in the cervical spine: a review. \u003cem\u003eInternational Orthopedics (SICOT)\u003c/em\u003e. 2019;43(4):797-805. doi:10.1007/s00264-018-4106-5\u003c/li\u003e\n\u003cli\u003eSaetia K, Cho D, Lee S, Kim DH, Kim SD. Ossification of the posterior longitudinal ligament: a review. \u003cem\u003eFOC\u003c/em\u003e. 2011;30(3):E1. doi:10.3171/2010.11.FOCUS10276\u003c/li\u003e\n\u003cli\u003eXiao B, Nagoshi N, Takeuchi A, et al. Imaging Comparison Between Chinese and Japanese Patients With Cervical Ossification of the Posterior Longitudinal Ligament. \u003cem\u003eSpine\u003c/em\u003e. 2018;43(23):E1376-E1383. doi:10.1097/BRS.0000000000002707\u003c/li\u003e\n\u003cli\u003eYan L, Gao R, Liu Y, He B, Lv S, Hao D. The Pathogenesis of Ossification of the Posterior Longitudinal Ligament. \u003cem\u003eAging and disease\u003c/em\u003e. 2017;8(5):570. doi:10.14336/AD.2017.0201\u003c/li\u003e\n\u003cli\u003eFujimori T, Watabe T, Iwamoto Y, Hamada S, Iwasaki M, Oda T. Prevalence, Concomitance, and Distribution of Ossification of the Spinal Ligaments: Results of Whole Spine CT Scans in 1500 Japanese Patients. \u003cem\u003eSpine\u003c/em\u003e. 2016;41(21):1668-1676. doi:10.1097/BRS.0000000000001643\u003c/li\u003e\n\u003cli\u003eNishimura S, Nagoshi N, Iwanami A, et al. Prevalence and Distribution of Diffuse Idiopathic Skeletal Hyperostosis on Whole-spine Computed Tomography in Patients With Cervical Ossification of the Posterior Longitudinal Ligament: A Multicenter Study. \u003cem\u003eClinical Spine Surgery: A Spine Publication\u003c/em\u003e. 2018;31(9):E460-E465. doi:10.1097/BSD.0000000000000701\u003c/li\u003e\n\u003cli\u003eMori K, Yoshii T, Hirai T, et al. Prevalence and distribution of ossification of the supra/interspinous ligaments in symptomatic patients with cervical ossification of the posterior longitudinal ligament of the spine: a CT-based multicenter cross-sectional study. \u003cem\u003eBMC Musculoskelet Disord\u003c/em\u003e. 2016;17(1):492. doi:10.1186/s12891-016-1350-y\u003c/li\u003e\n\u003cli\u003eMatsunaga S, Sakou T. Ossification of the Posterior Longitudinal Ligament of the Cervical Spine: Etiology and Natural History. \u003cem\u003eSpine\u003c/em\u003e. 2012;37(5):E309-E314. doi:10.1097/BRS.0b013e318241ad33\u003c/li\u003e\n\u003cli\u003eTauchi R, Lee SH, Peters C, Imagama S, Ishiguro N, Riew KD. Cervical Myeloradiculopathy due to Ossification of the Posterior Longitudinal Ligament with versus without Diffuse Idiopathic Spinal Hyperostosis. \u003cem\u003eGlobal Spine Journal\u003c/em\u003e. 2016;6(4):350-356. doi:10.1055/s-0035-1563722\u003c/li\u003e\n\u003cli\u003eKosaka T, Imakiire A, Mizuno F, Yamamoto K. Activation of nuclear factor \u0026kappa;B at the onset of ossification of the spinal ligaments. \u003cem\u003eJournal of Orthopedic Science\u003c/em\u003e. 2000;5(6):572-578. doi:10.1007/s007760070008\u003c/li\u003e\n\u003cli\u003eYonemori K, Imamura T, Ishidou Y, et al. Bone Morphogenetic Protein Receptors and Activin Receptors Are Highly Expressed in Ossified Ligament Tissues of Patients with Ossification of the Posterior Longitudinal Ligament. 1997;150(4).\u003c/li\u003e\n\u003cli\u003eNamgoong J, Lee YH, Ju AR, et al. Long-Term Follow-Up of Patients with Neck Pain Associated with Ossification of the Posterior Longitudinal Ligament Treated with Integrative Complementary and Alternative Medicine: A Retrospective Analysis and Questionnaire Survey. \u003cem\u003eJPR\u003c/em\u003e. 2022;Volume 15:1527-1541. doi:10.2147/JPR.S356280\u003c/li\u003e\n\u003cli\u003eYoshimura N, Nagata K, Muraki S, et al. Prevalence and progression of radiographic ossification of the posterior longitudinal ligament and associated factors in the Japanese population: a 3-year follow-up of the ROAD study. \u003cem\u003eOsteoporos Int\u003c/em\u003e. 2014;25(3):1089-1098. doi:10.1007/s00198-013-2489-0\u003c/li\u003e\n\u003cli\u003eAhmed O, Ramachandran K, Patel Y, et al. Diffuse Idiopathic Skeletal Hyperostosis Prevalence, Characteristics, and Associated Comorbidities: A Cross-Sectional Study of 1815 Whole Spine CT Scans. \u003cem\u003eGlobal Spine Journal\u003c/em\u003e. Published online October 26, 2022:219256822211368. doi:10.1177/21925682221136844\u003c/li\u003e\n\u003cli\u003eNguyen TCT, Yahara Y, Yasuda T, et al. Morphological characteristics of DISH in patients with OPLL and its association with high-sensitivity CRP: inflammatory DISH. \u003cem\u003eRheumatology\u003c/em\u003e. 2022;61(10):3981-3988. doi:10.1093/rheumatology/keac051\u003c/li\u003e\n\u003cli\u003eHirai T, Nishimura S, Yoshii T, et al. Associations between Clinical Findings and Severity of Diffuse Idiopathic Skeletal Hyperostosis in Patients with Ossification of the Posterior Longitudinal Ligament. \u003cem\u003eJCM\u003c/em\u003e. 2021;10(18):4137. doi:10.3390/jcm10184137\u003c/li\u003e\n\u003cli\u003eLi J, Zhang D, Shen Y. Impact of cervical sagittal parameters on axial neck pain in patients with cervical kyphosis. \u003cem\u003eJ Orthop Surg Res\u003c/em\u003e. 2020;15(1):434. doi:10.1186/s13018-020-01909-x\u003c/li\u003e\n\u003cli\u003eKorkmaz M, Ceylan CM, Korkmaz MD. Is cervical sagittal alignment associated with pain and disability in myofascial pain syndrome?: A cross-sectional study. \u003cem\u003eClinical Neurology and Neurosurgery\u003c/em\u003e. 2024;245:108458. doi:10.1016/j.clineuro.2024.108458\u003c/li\u003e\n\u003cli\u003eKato M, Nakamura H, Konishi S, et al. Effect of Preserving Paraspinal Muscles on Postoperative Axial Pain in the Selective Cervical Laminoplasty: \u003cem\u003eSpine\u003c/em\u003e. 2008;33(14):E455-E459. doi:10.1097/BRS.0b013e318178e607\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true},"keywords":"Diffuse idiopathic skeletal hyperostosis, Ossification, Posterior longitudinal ligament, Cervical spondylotic myelopathy, Imaging feature","lastPublishedDoi":"10.21203/rs.3.rs-8510413/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8510413/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eBoth ossification of the posterior longitudinal ligament (OPLL) and diffuse idiopathic skeletal hyperostosis (DISH) are characterized by abnormal calcification of the ligaments surrounding the spine and can be observed simultaneously in one patient. However, the association between cervical DISH and cevical OPLL has not been comprehensively investigated. This study aimed to investigate the influence of c-DISH on the progression of c-OPLL and to evaluate the clinical outcomes in patients with both c-DISH and c-OPLL.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eA total of 192 patients with c-OPLL were enrolled and divided into DISH(-) (n\u0026thinsp;=\u0026thinsp;152) and DISH(+) (n\u0026thinsp;=\u0026thinsp;40) groups on the basis of the presence or absence of c-DISH. C-OPLL severity was evaluated via the ossification index (OP index) and canal narrowing ratio (CNR) on CT images. The distribution characteristics were analyzed by c-OPLL type and ossification range, with a focus on the most affected segment. Radiographic measurements included the C2\u0026ndash;7 lordosis angle (CL angle), C7 slope, and C2\u0026ndash;7 sagittal vertical axis (CSVA). Clinical outcome was assessed via both JOA and VAS scores.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eBoth the OP index and the CNR were significantly greater in the DISH(+) group than in the DISH(-) group (P\u0026thinsp;\u0026lt;\u0026thinsp;0.01). Patients in the DISH(+) group had a greater proportion of continuous-type OPLL but lower segmental and local types than those in the DISH(-) group. Patients in the DISH(+) group also had a greater incidence of OPLL at the C2, C3, and C4 levels (P\u0026thinsp;\u0026lt;\u0026thinsp;0.05). Maximal ossification most frequently affects the C3 level in DISH(+) patients, whereas it affects the C5 level in DISH(-) patients. Compared with DISH(-) patients, DISH(+) patients had significantly poorer clinical outcomes both preoperatively and at the last follow-up. A significant negative correlation was observed between the CNR and both preoperative JOA scores.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eC-OPLL in patients with c-DISH tend to have a proximal cervical distribution, more extensive lesions, and more severe spinal canal occupation, leading to poor neurological function recovery.\u003c/p\u003e","manuscriptTitle":"Comparison of Imaging Features and Clinical Outcomes between Cervical Ossification of Posterior Longitudinal Ligament Patients with Cervical Diffuse Idiopathic Skeletal Hyperostosis and those without: A Retrospective Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-16 06:21:47","doi":"10.21203/rs.3.rs-8510413/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"editorInvitedReview","content":"","date":"2026-03-20T07:20:32+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"187725864714447551761284192735692519995","date":"2026-02-25T00:13:28+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2026-01-08T23:40:30+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2026-01-08T23:35:14+00:00","index":"","fulltext":""},{"type":"editorInvited","content":"","date":"2026-01-08T16:20:55+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2026-01-08T01:05:37+00:00","index":"","fulltext":""},{"type":"submitted","content":"BMC Musculoskeletal Disorders","date":"2026-01-08T01:00:38+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"bmc-musculoskeletal-disorders","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"bmsd","sideBox":"Learn more about [BMC Musculoskeletal Disorders](http://bmcmusculoskeletdisord.biomedcentral.com/)","snPcode":"","submissionUrl":"https://author-welcome.nature.com/12891","title":"BMC Musculoskeletal Disorders","twitterHandle":"BMC_series","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"stoa","reportingPortfolio":"BMC Series","inReviewEnabled":true,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"14dab2be-6e78-4060-a4f0-f5ab7797deb4","owner":[],"postedDate":"January 16th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[],"tags":[],"updatedAt":"2026-01-16T06:21:47+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-16 06:21:47","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8510413","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8510413","identity":"rs-8510413","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}