Long-Term Radiographic Outcomes of Dynesys Dynamic Stabilization in Lumbar Degenerative Disease: A 5-Year Retrospective Cohort Study

Long-Term Radiographic Outcomes of Dynesys Dynamic Stabilization in Lumbar Degenerative Disease: A 5-Year Retrospective Cohort 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 Long-Term Radiographic Outcomes of Dynesys Dynamic Stabilization in Lumbar Degenerative Disease: A 5-Year Retrospective Cohort Study Meng-Hsuan Hsieh, Kai-Chieh Chang, Chih-Ta Huang, Cheng-Ta Hsieh, and 1 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8943008/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Background Dynamic stabilization systems, such as Dynesys/Dynesys Top Loading (DTL), are developed to preserve segmental motion and mitigate adjacent segment degeneration (ASD) as alternatives to spinal fusion. However, long-term evidence supporting their effectiveness in maintaining a range of motion (ROM) remains limited. Methods In this retrospective study, 44 patients undergoing lumbar dynamic stabilization were evaluated using the Dynesys/DTL system, with ≥ 5 years of follow-up. Radiographic assessments included dynamic flexion–extension radiographs at different postoperative time points. Segmental and whole-spine ROM were measured, while the incidence of ASD was recorded. Results Segmental ROM partially recovered by 6 months (48% of baseline) but progressively declined, preserving only 28% at 2 years and 20% at 5 years (p < 0.05). In contrast, whole-spine ROM remained well preserved throughout the follow-up period, suggesting compensatory motion at nonoperated levels. ASD developed in 17 patients (38.6%), who demonstrated significantly lower segmental ROM preservation at 5 years than those without ASD (9% vs. 27%, p = 0.003). Among the factors analyzed, only sex exhibited a trend toward greater ROM loss, with female patients showing a greater decline. Conclusion Despite achieving early motion preservation, Dynesys/DTL systems do not maintain segmental ROM beyond 5 years and do not consistently prevent ASD. These findings indicate that Dynesys/DTL may function more as a semi-rigid fixation construct than as a truly dynamic stabilization, highlighting the need for improved biomechanical design and further long-term studies. Lumbar Vertebrae Range of Motion Articular Internal Fixators Intervertebral Disc Degeneration Spinal Diseases Figures Figure 1 Figure 2 Figure 3 Figure 4 Background In spinal surgery, surgeons typically aim to achieve two key objectives: effective neural decompression and the maintenance of spinal stability. These goals often conflict because adequate decompression may require altering supportive anatomical structures, potentially compromising spinal stability. Conversely, prioritizing stability may limit the extend of decompression. Consequently, spinal fusion has become a widely adopted strategy for addressing both objectives simultaneously. However, fusion eliminates motion at the operated segment and contributes to progressive degeneration at adjacent levels [ 1 , 2 ]. To mitigate the limitations associated with spinal fusion, various motion-preserving surgical techniques and implant systems have been developed. Among these, motion-preserving procedures, such as artificial nucleus replacement, artificial disc replacement, and posterior dynamic stabilization, have gained significant attention [ 3 , 4 ]. For example, the Dynamic Neutralization System (Dynesys), first introduced by Dubois et al. [ 5 ], has been used in France since 1994. To date, Dynesys remains the most widely used posterior non-fusion pedicle screw-based stabilization system [ 6 ]. Several clinical studies show that Dynesys is an effective option for managing degenerative lumbar spine conditions, with reported benefits including symptom improvement, preservation of segmental motion, and a lower incidence of adjacent segment degeneration (ASD) [ 2 , 7 , 8 ]. However, most of these studies often include follow-up periods of approximately 2–3 years. Therefore, this study aims to evaluate the long-term ability of the Dynesys system to preserve the segmental range of motion (ROM) over a follow-up period of > 5 years, building upon previous findings, including those of our previous study [ 9 ], and to identify potential factors influencing motion preservation at the surgical level. Materials and Methods Study design and population This retrospective study was conducted to evaluate changes in ROM in patients who underwent lumbar surgery using the Dynesys Top Loading (Dynesys/DTL). Overall, 62 patients received Dynesys/DTL instrumentation for lumbar degenerative diseases, including spinal stenosis and/or herniated intervertebral discs (HIVD), at our hospital between August 2008 and August 2017. Surgical indications included younger patients with symptomatic lumbar degenerative conditions, with or without HIVD or spinal stenosis, and without radiographic evidence of instability or osteoporosis. Bone mineral density was evaluated in patients aged > 60. Contraindications included elderly patients with osteoporosis, those with confirmed instability (grade II spondylolisthesis or higher, or advanced facet joint degeneration), and patients with isolated HIVD unsuitable for posterior fusion surgery. During the follow-up period, five screws fractured in three patients, with two other patients requiring implant removal because of persistent lower back pain. Fourteen patients had a postoperative follow-up period of < 5 years or were lost to follow-up, resulting in a final cohort of 44 patients who met the study criteria. The study involved a comprehensive review of medical records and radiological imaging, including plain abdominal X-rays and dynamic lumbar X-rays obtained preoperatively and postoperative at 6 months, 2 years, and 5 years. Additionally, lumbar spine magnetic resonance imaging (MRI) findings and clinical evaluations were reviewed. All preoperative and postoperative radiologic evaluations and clinical outcomes were analyzed for eligible patients. This study aims to offer valuable insights into the effects of Dynesys instrumentation on ROM in patients with specific lumbar degenerative conditions. Radiologic evaluations Radiologic evaluations were conducted at several time points: preoperatively and postoperatively at 1 month, 3 months, 6 months, 2 years, and 5 years. Preoperative MRI was used to confirm that the clinical symptoms of each patient aligned with the imaging findings, thereby supporting the diagnosis of lumbar degenerative conditions. Dynamic radiographic evaluations were conducted using lumbar spine flexion–extension views. Angular motion during flexion and extension was measured at each time point. Two independent research assistants completed the angle measurements, and the mean values were recorded. The ROM at both the index level (operative segment) (Fig. 1 ) and across the entire lumbar spine (L1–S1) was calculated as the difference between the extension angle and the flexion angle (Fig. 2 ). Additionally, ASD was evaluated over the 5-year follow-up period using radiographic imaging. ASD was defined as any of the following radiographic changes, regardless of clinical symptoms: loss of disc height, progression of disc degeneration, spinal stenosis, segmental instability, or hypertrophic facet joint arthropathy [ 8 , 10 ]. Statistical analysis Statistical analyses were performed using IBM SPSS Statistics for Windows, Version 26 (IBM Corp., Armonk, NY, USA). Radiologic data collected from 1 month postoperatively onward were analyzed using paired t tests, comparing each follow-up interval with the 6-month postoperative measurements because ROM typically peaks at 6 months and subsequently declines. Differences between patients who developed ASD and those who did not were evaluated at each time point using independent-samples t -tests and the nonparametric Mann–Whitney U test. A p -value of < 0.05 was considered statistically significant. Results Overall, 44 patients, comprising 28 males and 16 females, were included in the analysis. The mean age was 51.5 years (Table 1 ). Statistical analysis revealed a postoperative decrease in segmental ROM at the index level. During the first 6 months after surgery, partial recovery of segmental ROM was observed, reaching its highest level of motion preservation (48%) at 6 months (Table 2 ). However, the segmental ROM gradually declined after 6 months, with only 28% (p = 0.0136) and 20% (p = 0.0003) preserved at 2 years and 5 years postoperatively, respectively. Both values were significantly lower than the level of motion preservation observed at 6 months (Table 3 ). Table 1 Demographic characteristics of the 44 patients Variable Mean SD Age (years) 51.5 12.7 N % Sex Male 28 63.6 Female 16 36.4 Operation type Dynesys 9 20.5 DTL 35 79.5 Abbreviations: DTL, Dynesys Top-Loading system; SD, standard deviation Table 2 Postoperative ROM at the index level and across the whole lumbar spine Time point ROM of index level (°) ROM of whole L-spine (°) ROM loss of index level (°) ROM loss of whole L-spine (°) Pre-op 14.8 29.38 0 0 Post-op 1 month 3.21 16.33 10.75 12.75 Post-op 3 months 3.40 19.60 9.59 9.08 Post-op 6 months 4.68 22.70 8.75 3.45 Post-op 12 months 3.72 23.49 9.56 5.49 Post-op 24 months 3.59 26.06 10.79 4.25 Post-op 60 months 2.63 25.54 11.49 4.80 Abbreviations: L-spine, lumbar spine; Pre-op, preoperative; Post-op, postoperative; ROM, range of motion Table 3 Post-operative ROM preservation ratio compared to preoperative ROM Follow-up time point Index level (%) p-value Whole L-spine (%) p- value Post-op 1 month 33 0.198 73 *0.026 Post-op 3 months 41 0.122 78 0.651 Post-op 6 months 48 N/A 100 N/A Post-op 12 months 35 0.428 100 0.586 Post-op 24 months 28 *0.014 100 0.558 Post-op 60 months 20 *<0.001 98 0.474 * p < 0.05 indicates a statistically significant difference compared with postoperative 6 months (paired t-test). Abbreviations: N/A, not applicable; ROM, range of motion In contrast, whole-spine ROM decreased immediately after surgery, with only 73% of motion preserved 1 month postoperatively. Mobility improved significantly over time, and at 6 months post-postoperatively, whole-spine ROM was well preserved. The follow-up extended beyond 5 years, and whole-spine ROM showed no significant decline, remaining well preserved. While overall spinal mobility was maintained, ROM at the index (operative) segment was not preserved at the 5-year follow-up evaluation (Table 3 ). These findings suggest that the preserved ROM in non-operated segments reflects compensatory motion, as the operated level is unable to maintain its original mobility. Furthermore, ASD was evaluated in this study. When comparing patients with and without ASD, no significant differences in whole-spine ROM preservation were observed during postoperative follow-up. However, at the 5-year follow-up, segmental ROM preservation was 9% in patients with ASD (17 patients) and 27% in patients without ASD (27 patients), showing a statistically significant difference (p = 0.003) (Fig. 3 ). No other postoperative time points showed significant differences. In the subgroup analysis, factors such as sex, age, number of operated levels, and whether a discectomy was performed were examined in relation to ROM preservation. Sex-based analysis revealed that female patients experienced a greater reduction in ROM than male patients. This difference reached statistical significance at 2 years postoperatively (p = 0.023) and demonstrated a continued, although not statistically significant, trend at 5 years (p = 0.071). In contrast, none of the other examined factors, including age, number of operated levels, or whether discectomy was performed, were significantly associated with ROM preservation or ASD occurrence (Fig. 4 ). Discussion Lumbar spine disorders are common and represent complex pathologies associated with age-related degeneration. Degeneration typically involves various interrelated structures, including the intervertebral discs, vertebral bodies with osteophyte formation, and thickening of the surrounding ligaments, ultimately leading to spinal stenosis or spondylolisthesis. In the early stages of symptom development, patients often respond well to medical therapy and conservative physical treatments. However, in advanced stages characterized by severe neural compression or progressive structural deformity, surgical intervention may be required. The primary objectives of spinal surgery are adequate neural decompression and preservation of spinal stability. When the underlying pathology can be resolved through decompression without compromising anatomical stability, less invasive procedures such as discectomy or laminectomy may suffice. However, when the symptoms of a patient are associated with compromised structural stability, or when decompression alone may induce postoperative instability, various devices or implants may be required to achieve adequate decompression while preserving stability [ 11 ]. Spinal fusion remains a conventional treatment approach for patients with structural deformity, preoperative instability, or a high risk of postoperative iatrogenic instability. Nevertheless, fusion is associated with several potential limitations, including ASD caused by loss of motion at the fused levels, pseudoarthrosis, infection, and implant failure [ 12 ]. The primary concern is that rigid instrumentation and fusion increase mechanical stress on adjacent segments, potentially leading to degenerative changes at motion levels caudal or cephalad to the fused segment [ 9 ]. In response to the limitations of spinal fusion, several devices and implants have been developed to mitigate ASD after fusion while preserving the required postoperative stability. These devices include artificial disc replacements and dynamic stabilization systems implanted during posterior procedures [ 12 – 16 ]. Since Roy-Camille and Saillant first introduced posterior fusion with transpedicular screws in 1984, this technique has been widely used in spine surgery because of its ability to provide immediate segmental stability. Therefore, most motion-preserving devices are based on posterior, non-fusion pedicle screw-based stabilization. The Graft ligament, the first instrument of these devices introduced in the 1990s, has theoretical limitations, including the potential to increase lateral recess and foraminal narrowing, ultimately increasing the risk of nerve root compression. Additionally, studies report unfavorable outcomes, leading to recommendations against the use of this procedure [ 6 , 9 , 17 ]. Dynesys, a posterior non-fusion spinal stabilization system developed by Dubois et al. [ 18 ] in 1991, was clinically introduced in 1994. During flexion, motion is regulated by tension to the cord, while during extension, the cylindrical polymer spacers function as partially compressible elements, allowing limited extension. Theoretically, this design reduces disc loading, thereby preventing the posterior annular compression associated with Graft ligamentoplasty [ 9 , 19 ]. Since its introduction, Dynesys has been widely used in spine surgery as a motion-preserving system. Most studies report that Dynesys provides clinical outcomes comparable to—or, in some cases, better than—those achieved with traditional posterior fusion. The system demonstrates advantages in certain domains, including preserving segmental ROM, reduced operative time and blood loss, shorter length of hospital stays, lower rates of ASD, and fewer complications [ 12 , 20 ]. Zhou et al. conducted a meta-analysis of 17 studies involving 1,296 patients, showing that Dynesys produces significantly lower postoperative Visual Analogue Scale (VAS) scores for both low back and leg pain than the traditional fusion. Additionally, the Dynesys group demonstrated a lower rate of surgical revision than the fusion group. The ROM at the stabilized segments in the fusion group decreased significantly, while the ROM at the adjacent segments increased significantly compared to those of the Dynesys group [ 8 ]. Similarly, Wang et al conducted a meta-analysis involving 17 studies, showing no significant differences between the Dynesys and fusion groups in the Oswestry Disability Index, VAS scores for leg or back pain, or L2–S1 ROM. However, the operation time, intraoperative blood loss, length of hospital stays, and complication rates are significantly lower in the Dynesys group than in the fusion group. Furthermore, studies report additional benefits of Dynesys, particularly in reducing ASD and preserving ROM [ 12 ]. ASD is widely recognized as the most significant complication following spinal fusion surgery, and its likelihood increases with advancing age. Loss of ROM at the index level is a key factor related to ASD. Therefore, the primary focus of this study is to assess the long-term effectiveness of Dynesys in preserving ROM [ 9 ]. In this study, whole-spine ROM initially declined after surgery but recovered and remained well preserved at the 5-year postoperative follow-up. Additionally, segmental ROM was well preserved and reached its highest value at 6 months after surgery. However, it gradually decreased over time, with a significant decline observed at the 5-year follow-up, with segmental ROM preservation reducing to < 20% of the preoperative value. These findings suggest that ROM in the operative segments continues to decrease over the long term after implantation of the Dynesys/DTL system. Additionally, ASD continued to develop during the long-term follow-up. At the 5-year postoperative assessment, ASD was more prevalent in the group demonstrating lower ROM preservation. Studies [ 8 , 20 – 23 ] show that dynamic stabilization systems produce good clinical outcomes, preserve ROM at the stabilized segments, and limit hypermobility at adjacent segments, thereby reducing the risk of ASD. However, these studies generally report a follow-up period of < 3 years. When follow-up extends beyond 5 years, more complications occur. For example, Zhang et al. [ 8 ] report that, at a minimum follow-up of 72 months, the upper adjacent segment demonstrates significantly increased ROM and decreased disc height compared to the preoperative values. Yeh et al. [ 24 ] report that patients undergoing Dynesys surgery exhibit a significant decrease in ROM and a higher incidence of facet joint degeneration or spontaneous fusion at the index level than those undergoing microdiscectomy. These results were observed over a mean follow-up period of 36 ± 16.8 months. Furthermore, Chen et al [ 4 ] investigated a cohort of patients who presented with asymptomatic ASD before undergoing Dynesys surgery. The study reports that progression to symptomatic ASD requiring reoperation occurs at a mean follow-up of 7.22 years, with overweight patients demonstrating the strongest correlation with symptom progression. These findings support our findings, indicating that Dynesys surgery provides initial benefits to patients. However, patients showed a significant decline in ROM and an increased susceptibility to ASD during long-term follow-up. The early benefits of the procedure may diminish over time, particularly in specific patient subgroups. However, this decline was not associated with factors such as prior discectomy or the use of multilevel instrumentation. Although the ability of the Dynesys/DTL system to preserve segmental ROM remains uncertain, the cohort demonstrated that 61.3% (27/44) of patients did not develop ASD within 5 years postoperatively. These findings suggest that the Dynesys/DTL systems may offer partial protection against, or delay in the progression of ASD. However, substantial long-term ROM reduction remains common, with a potential higher rate of ASD with extended follow-up [ 4 ]. Overall, while these systems may mitigate early degeneration, they are inadequate for maintaining long-term segmental motion or preventing ASD. In summary, although studies show that dynamic stabilization systems preserve ROM and reduce the risk of ASD, most are limited to short-term follow-up of only 2–3 years. This study, consistent with previous studies, indicates that the Dynesys/DTL system generally does not maintain segmental ROM or prevent ASD beyond 5 years. Nonetheless, these findings do not entirely discredit the potential value of pedicle-based dynamic stabilizers. We hypothesize that the loss of motion preservation may relate to excessive inter-screw spacing. Based on the protocol of the manufacturer, screws are distracted with approximately 2 N of force before placement of a spacer of corresponding length. This force may produce an overly rigid construct, highlighting the potential need for refinements in sizing or design. This study has some limitations. First, as a retrospective case analysis, the study is prone to potential selection bias owing to incomplete or missing medical records, necessitating the exclusion of certain cases. Second, the relatively small sample size (n = 44) limits the overall statistical power and may prevent the generalizability of the findings. Finally, imaging evaluations were performed manually, potentially introducing the risk of minor measurement deviations. Future studies could incorporate artificial intelligence–assisted image analysis to enhance measurement accuracy and standardization, thereby minimizing potential errors. Conclusion Preserving physiological motion while maintaining spinal stability remains a fundamental goal in spine surgery. These findings suggest that the current Dynesys/DTL systems do not adequately achieve this balance. Over long-term follow-up, segmental fusion with progressive loss of ROM was frequently observed after Dynesys system implantation, and the occurrence of ASD became increasingly evident beyond 5 years postoperatively. These findings indicate that the Dynesys/DTL system may function as a semi-rigid fixation construct rather than as a truly dynamic stabilization device. This finding highlights the need for further biomechanical research and continued refinement of dynamic stabilization system designs. Abbreviations DTL Dynesys Top Loading ASD adjacent segment degeneration ROM range of motion HIVD herniated intervertebral discs MRI magnetic resonance imaging VAS visual analogue scale Declarations Ethics approval This research paper was approved by the Institutional Review Board of Cathay General Hospital, Taiwan (approval number: CGH-P112068). All procedures were conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective design of the study. Consent for publication Not applicable. Availability of data and materials All data generated and analysed in this study are fully presented within the article and its tables/figures. Competing interests Meng-Hsuan Hsieh reports no conflict of interest. Kai-Chieh Chang reports no conflict of interest. Chih-Ta Huanga reports no conflict of interest. Cheng-Ta Hsieh reports no conflict of interest. Chih-Ju Chang reports no conflict of interest. Funding This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Author contributions Meng-Hsuan Hsieh: study design, data collection, data analysis and manuscript preparation; Kai-Chieh Chang: investigation, data collection, and data analysis; Chih-Ta Huang: investigation, data collection, and data analysis; Cheng-Ta Hsieh: clinical coordination and data checking; and Chih-Ju Chang: study design, manuscript revision for intellectual content, and project supervision. All authors have read and approved the final version of the manuscript. Acknowledgements Not applicable Authors’ Information Academic degrees and email addresses of all authors: Meng-Hsuan Hsieh, MD: [email protected] Kai-Chieh Chang, MD: [email protected] Chih-Ta Huang, MD: [email protected] Cheng-Ta Hsieh, MD, PhD: [email protected] Chih-Ju Chang, MD, PhD: [email protected] References Peng BG, Gao CH. Is Dynesys dynamic stabilization system superior to posterior lumbar fusion in the treatment of lumbar degenerative diseases? World J Clin Cases. 2020;8:5496–500. Gao Q, Yang D, Yuan Z. Clinical observation of dynesys dynamic internal fixation system in the treatment of lumbar degenerative diseases. Panminerva Med. 2021. St-Pierre GH, Jack A, Siddiqui MM, Henderson RL, Nataraj A. Nonfusion does not prevent adjacent segment disease: Dynesys long-term outcomes with minimum five-year follow-up. Spine (Phila Pa 1976). 2016;41:265–73. Chen KJ, Lai CY, Chiu LT. Adjacent segment disease following Dynesys stabilization for lumbar disorders: a case series of mid- and long-term follow-ups. World J Clin Cases. 2021;9:10850–60. Stoll TM, Dubois G, Schwarzenbach O. The dynamic neutralization system for the spine: a multi-center study of a novel non-fusion system. Eur Spine J. 2002;11(2suppl 2):S170–8. Anand N, Baron EM. Role of dynesys as pedicle-based nonfusion stabilization for degenerative disc disorders. Adv Orthop. 2012;2012:218385. Khalifé M, Devriese F, Ferrero E, Zadegan F, Ajavon L, Mazel C. Dynesys® dynamic stabilization outcomes in degenerative spine surgery. Acta Orthop Belg. 2021;87:795–803. Zhou LP, Zhang RJ, Wang JQ. Medium and long-term radiographic and clinical outcomes of Dynesys dynamic stabilization versus instrumented fusion for degenerative lumbar spine diseases. BMC Surg. 2023;23:46. Hsieh CT, Chang CJ, Su IC, Lin LY. Clinical experiences of dynamic stabilizers: Dynesys and Dynesys top loading system for lumbar spine degenerative disease. Kaohsiung J Med Sci. 2016;32:207–15. Hilibrand AS, Robbins M. Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion? Spine J 2004;4(suppl 6):S190–194. Bothmann M, Kast E, Boldt GJ, Oberle J. Dynesys fixation for lumbar spine degeneration. Neurosurg Rev. 2008;31:189–96. Wang H, Peng J, Zeng Q. Dynesys system vs posterior decompression and fusion for the treatment of lumbar degenerative diseases. Med (Baltim). 2020;99:e19784. Bredin S, Demay O, Mensa C, Madi K, Ohl X. 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Schmoelz W, Huber JF, Nydegger T, Claes L, Wilke HJ. Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure. Eur Spine J. 2006;15:1276–85. Hu Y, Gu YJ, Xu RM, Zhou LJ, Ma WH. Short-term clinical observation of the Dynesys neutralization system for the treatment of degenerative disease of the lumbar vertebrae. Orthop Surg. 2011;3:167–75. Yu SW, Yang SC, Ma CH, Wu CH, Yen CY, Tu YK. Comparison of Dynesys posterior stabilization and posterior lumbar interbody fusion for spinal stenosis L4L5. Acta Orthop Belg. 2012;78:230–9. Fei H, Xu J, Wang S, Xie Y, Ji F, Xu Y. Comparison between posterior dynamic stabilization and posterior lumbar interbody fusion in the treatment of degenerative disc disease: a prospective cohort study. J Orthop Surg Res. 2015;10:87. Li HP, Li F, Guan K, Zhao GM, Shan JL, Sun TS. Dynesys dynamic stabilization system for the lumbar degenerative disease: a preliminary report from China. Chin Med J. 2013;126:4265–9. Yeh MY, Kuo CH, Wu JC. Changes of facet joints after dynamic stabilization: continuous degeneration or slow fusion? World Neurosurg. 2018;113:e45–50. Additional Declarations No competing interests reported. Cite Share Download PDF Status: Posted Version 1 posted 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-8943008","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":599559995,"identity":"789b19c7-0bca-4d31-8c9a-780dd02aaf6d","order_by":0,"name":"Meng-Hsuan Hsieh","email":"","orcid":"","institution":"Cathay General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Meng-Hsuan","middleName":"","lastName":"Hsieh","suffix":""},{"id":599559996,"identity":"8d342e3f-9d05-4c81-b99f-446db3ce3b4c","order_by":1,"name":"Kai-Chieh Chang","email":"","orcid":"","institution":"Cathay General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Kai-Chieh","middleName":"","lastName":"Chang","suffix":""},{"id":599559998,"identity":"85588899-fbc5-4ed7-8467-cd7a977a734e","order_by":2,"name":"Chih-Ta Huang","email":"","orcid":"","institution":"Cathay General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Chih-Ta","middleName":"","lastName":"Huang","suffix":""},{"id":599560000,"identity":"f3f99a93-26bb-40ac-9169-8dac30392fee","order_by":3,"name":"Cheng-Ta Hsieh","email":"","orcid":"","institution":"Cathay General Hospital","correspondingAuthor":false,"prefix":"","firstName":"Cheng-Ta","middleName":"","lastName":"Hsieh","suffix":""},{"id":599560001,"identity":"d52127dc-cc63-48e2-a998-4b4b3fbb2687","order_by":4,"name":"Chih-Ju Chang","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAABDElEQVRIiWNgGAWjYDACZjbGAwwMQMTA//DhhwobIIOx8QABLQxQLTzMxhJn0kBaGvBrYUBoYRPgbTsMFsOrRbedLeHAh5o78ub8a48xSLadt1vbfhhoS41NNC4tZofZDhycceyZ4c4Z79IeFJy7nbztTCJQy7G03AacWtgbDvM2HGbccOOAuYFE2e1kswNALYwNh/Fr+dtw2B6oxUyCh+1cstn5h4S0sB04DFSQuOF8D1BL2wE7sxsEbWFLONhz7HDyhhtsycBATk4wuwG0JQGfX84fM3zwo+aw7Ybzhw8Co9LO3ux8+sMHH2pscGpBAIkEMJUIVplAUDkI8B8AU/ZEKR4Fo2AUjIIRBQACoXPe7Vt1GwAAAABJRU5ErkJggg==","orcid":"","institution":"Cathay General Hospital","correspondingAuthor":true,"prefix":"","firstName":"Chih-Ju","middleName":"","lastName":"Chang","suffix":""}],"badges":[],"createdAt":"2026-02-23 05:08:56","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8943008/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8943008/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":104170730,"identity":"a74e11e1-091a-49d2-be0d-44bf24d3730a","added_by":"auto","created_at":"2026-03-08 14:50:05","extension":"png","order_by":1,"title":"Figure 1","display":"","copyAsset":false,"role":"figure","size":10232550,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of ROM at the index level. (A) Preoperative extension radiograph showing the index Cobb angle measured between the L3 and L5 endplates. (B) Preoperative flexion radiograph showing the L3–L5 index Cobb angle; the preoperative ROM is calculated as 24.7° − 9.3° = 15.4°. (C) Postoperative 3-month extension radiograph demonstrating the L3–L5 index Cobb angle. (D) Postoperative 3-month flexion radiograph demonstrating the L3–L5 index Cobb angle; the postoperative 3-month ROM is calculated as 25.6° − 18.9° = 6.7°.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviation:\u003c/strong\u003e ROM, range of motion\u003c/p\u003e","description":"","filename":"Figure1.png","url":"https://assets-eu.researchsquare.com/files/rs-8943008/v1/0caecb903222d647b666d5d8.png"},{"id":104170731,"identity":"ddba0d49-54d3-4437-a328-eba8fb0554ee","added_by":"auto","created_at":"2026-03-08 14:50:05","extension":"png","order_by":2,"title":"Figure 2","display":"","copyAsset":false,"role":"figure","size":9554462,"visible":true,"origin":"","legend":"\u003cp\u003eMeasurement of the whole lumbar spine ROM. (A) Preoperative extension radiograph showing the Cobb angle measured between the superior endplates of L1 and S1. (B) Preoperative flexion radiograph showing the L1–S1 Cobb angle; the preoperative whole-lumbar ROM is calculated as 45.8° − 10.1° = 35.7°. (C) Postoperative 3-month extension radiograph demonstrating the L1−S1 Cobb angle. (D) Postoperative 3-month flexion radiograph demonstrating the L1−S1 Cobb angle; the postoperative 3-month whole-lumbar ROM is calculated as 44.2° − 35.2° = 9.0°.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviation:\u003c/strong\u003e ROM, range of motion\u003c/p\u003e","description":"","filename":"Figure2.png","url":"https://assets-eu.researchsquare.com/files/rs-8943008/v1/5165ed3988de4bcd10987052.png"},{"id":104170729,"identity":"2e046627-3bc3-4124-94da-90011a4a68f1","added_by":"auto","created_at":"2026-03-08 14:50:05","extension":"png","order_by":3,"title":"Figure 3","display":"","copyAsset":false,"role":"figure","size":5354106,"visible":true,"origin":"","legend":"\u003cp\u003eROM preservation ratio at the index level during scheduled follow-up in patients with and without ASD. At the 5-year follow-up, 17 patients developed ASD, showing a statistically significant decrease in ROM preservation compared to the 27 patients in the non-ASD group. * \u003cem\u003ep\u003c/em\u003e-value = 0.001.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviations: \u003c/strong\u003eASD, adjacent segment disease; ROM, range of motion\u003c/p\u003e","description":"","filename":"Figure3.png","url":"https://assets-eu.researchsquare.com/files/rs-8943008/v1/6d7d75db2b8d4b7ff0ea6f03.png"},{"id":104170732,"identity":"2c202da8-bdc6-4ebf-af25-99eba1a2fe67","added_by":"auto","created_at":"2026-03-08 14:50:05","extension":"png","order_by":4,"title":"Figure 4","display":"","copyAsset":false,"role":"figure","size":14761620,"visible":true,"origin":"","legend":"\u003cp\u003eSubgroup analysis of ROM preservation. Female patients show a greater decline in ROM than male patients, reaching statistical significance at 2 years postoperatively (*\u003cem\u003ep\u003c/em\u003e = 0.023) and demonstrating a similar trend at 5 years, although non-significant (\u003cem\u003ep\u003c/em\u003e = 0.071). None of the other evaluated variables showed a statistically significant association with ROM preservation.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAbbreviation:\u003c/strong\u003e ROM, range of motion\u003c/p\u003e","description":"","filename":"Figure4.png","url":"https://assets-eu.researchsquare.com/files/rs-8943008/v1/4b33d3c8f0e8dfc55efc9c10.png"},{"id":106959706,"identity":"1ce76ce9-66da-4b84-bde3-d18cd559dad6","added_by":"auto","created_at":"2026-04-15 09:13:57","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":37598758,"visible":true,"origin":"","legend":"","description":"","filename":"manuscript.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8943008/v1/4320b85b-7e0a-4ec5-a7be-855066750c5d.pdf"}],"financialInterests":"No competing interests reported.","formattedTitle":"Long-Term Radiographic Outcomes of Dynesys Dynamic Stabilization in Lumbar Degenerative Disease: A 5-Year Retrospective Cohort Study","fulltext":[{"header":"Background","content":"\u003cp\u003eIn spinal surgery, surgeons typically aim to achieve two key objectives: effective neural decompression and the maintenance of spinal stability. These goals often conflict because adequate decompression may require altering supportive anatomical structures, potentially compromising spinal stability. Conversely, prioritizing stability may limit the extend of decompression. Consequently, spinal fusion has become a widely adopted strategy for addressing both objectives simultaneously. However, fusion eliminates motion at the operated segment and contributes to progressive degeneration at adjacent levels [\u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e1\u003c/span\u003e, \u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e]. To mitigate the limitations associated with spinal fusion, various motion-preserving surgical techniques and implant systems have been developed. Among these, motion-preserving procedures, such as artificial nucleus replacement, artificial disc replacement, and posterior dynamic stabilization, have gained significant attention [\u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e3\u003c/span\u003e, \u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. For example, the Dynamic Neutralization System (Dynesys), first introduced by Dubois et al. [\u003cspan citationid=\"CR5\" class=\"CitationRef\"\u003e5\u003c/span\u003e], has been used in France since 1994. To date, Dynesys remains the most widely used posterior non-fusion pedicle screw-based stabilization system [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e]. Several clinical studies show that Dynesys is an effective option for managing degenerative lumbar spine conditions, with reported benefits including symptom improvement, preservation of segmental motion, and a lower incidence of adjacent segment degeneration (ASD) [\u003cspan citationid=\"CR2\" class=\"CitationRef\"\u003e2\u003c/span\u003e, \u003cspan citationid=\"CR7\" class=\"CitationRef\"\u003e7\u003c/span\u003e, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eHowever, most of these studies often include follow-up periods of approximately 2\u0026ndash;3 years. Therefore, this study aims to evaluate the long-term ability of the Dynesys system to preserve the segmental range of motion (ROM) over a follow-up period of \u0026gt;\u0026thinsp;5 years, building upon previous findings, including those of our previous study [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e], and to identify potential factors influencing motion preservation at the surgical level.\u003c/p\u003e"},{"header":"Materials and Methods","content":"\u003cdiv id=\"Sec3\" class=\"Section2\"\u003e \u003ch2\u003eStudy design and population\u003c/h2\u003e \u003cp\u003eThis retrospective study was conducted to evaluate changes in ROM in patients who underwent lumbar surgery using the Dynesys Top Loading (Dynesys/DTL). Overall, 62 patients received Dynesys/DTL instrumentation for lumbar degenerative diseases, including spinal stenosis and/or herniated intervertebral discs (HIVD), at our hospital between August 2008 and August 2017.\u003c/p\u003e \u003cp\u003eSurgical indications included younger patients with symptomatic lumbar degenerative conditions, with or without HIVD or spinal stenosis, and without radiographic evidence of instability or osteoporosis. Bone mineral density was evaluated in patients aged\u0026thinsp;\u0026gt;\u0026thinsp;60. Contraindications included elderly patients with osteoporosis, those with confirmed instability (grade II spondylolisthesis or higher, or advanced facet joint degeneration), and patients with isolated HIVD unsuitable for posterior fusion surgery.\u003c/p\u003e \u003cp\u003eDuring the follow-up period, five screws fractured in three patients, with two other patients requiring implant removal because of persistent lower back pain. Fourteen patients had a postoperative follow-up period of \u0026lt;\u0026thinsp;5 years or were lost to follow-up, resulting in a final cohort of 44 patients who met the study criteria.\u003c/p\u003e \u003cp\u003eThe study involved a comprehensive review of medical records and radiological imaging, including plain abdominal X-rays and dynamic lumbar X-rays obtained preoperatively and postoperative at 6 months, 2 years, and 5 years. Additionally, lumbar spine magnetic resonance imaging (MRI) findings and clinical evaluations were reviewed.\u003c/p\u003e \u003cp\u003eAll preoperative and postoperative radiologic evaluations and clinical outcomes were analyzed for eligible patients. This study aims to offer valuable insights into the effects of Dynesys instrumentation on ROM in patients with specific lumbar degenerative conditions.\u003c/p\u003e \u003c/div\u003e\n\u003ch3\u003eRadiologic evaluations\u003c/h3\u003e\n\u003cp\u003eRadiologic evaluations were conducted at several time points: preoperatively and postoperatively at 1 month, 3 months, 6 months, 2 years, and 5 years. Preoperative MRI was used to confirm that the clinical symptoms of each patient aligned with the imaging findings, thereby supporting the diagnosis of lumbar degenerative conditions.\u003c/p\u003e \u003cp\u003eDynamic radiographic evaluations were conducted using lumbar spine flexion\u0026ndash;extension views. Angular motion during flexion and extension was measured at each time point. Two independent research assistants completed the angle measurements, and the mean values were recorded. The ROM at both the index level (operative segment) (Fig.\u0026nbsp;\u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003e1\u003c/span\u003e) and across the entire lumbar spine (L1\u0026ndash;S1) was calculated as the difference between the extension angle and the flexion angle (Fig.\u0026nbsp;\u003cspan refid=\"Fig2\" class=\"InternalRef\"\u003e2\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eAdditionally, ASD was evaluated over the 5-year follow-up period using radiographic imaging. ASD was defined as any of the following radiographic changes, regardless of clinical symptoms: loss of disc height, progression of disc degeneration, spinal stenosis, segmental instability, or hypertrophic facet joint arthropathy [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e10\u003c/span\u003e].\u003c/p\u003e \u003cdiv id=\"Sec5\" class=\"Section2\"\u003e \u003ch2\u003eStatistical analysis\u003c/h2\u003e \u003cp\u003eStatistical analyses were performed using IBM SPSS Statistics for Windows, Version 26 (IBM Corp., Armonk, NY, USA). Radiologic data collected from 1 month postoperatively onward were analyzed using paired \u003cem\u003et\u003c/em\u003e tests, comparing each follow-up interval with the 6-month postoperative measurements because ROM typically peaks at 6 months and subsequently declines. Differences between patients who developed ASD and those who did not were evaluated at each time point using independent-samples \u003cem\u003et\u003c/em\u003e-tests and the nonparametric Mann\u0026ndash;Whitney \u003cem\u003eU\u003c/em\u003e test. A \u003cem\u003ep\u003c/em\u003e-value of \u0026lt;\u0026thinsp;0.05 was considered statistically significant.\u003c/p\u003e \u003c/div\u003e"},{"header":"Results","content":"\u003cp\u003eOverall, 44 patients, comprising 28 males and 16 females, were included in the analysis. The mean age was 51.5 years (Table \u003cspan class=\"InternalRef\"\u003e1\u003c/span\u003e). Statistical analysis revealed a postoperative decrease in segmental ROM at the index level. During the first 6 months after surgery, partial recovery of segmental ROM was observed, reaching its highest level of motion preservation (48%) at 6 months (Table \u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e). However, the segmental ROM gradually declined after 6 months, with only 28% (p\u0026thinsp;=\u0026thinsp;0.0136) and 20% (p\u0026thinsp;=\u0026thinsp;0.0003) preserved at 2 years and 5 years postoperatively, respectively. Both values were significantly lower than the level of motion preservation observed at 6 months (Table \u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e).\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003ctable id=\"Tab1\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003eDemographic characteristics of the 44 patients\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eVariable\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eMean\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eSD\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAge (years)\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e51.5\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.7\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e%\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eSex\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eMale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e63.6\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eFemale\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e16\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e36.4\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eOperation type\u003c/strong\u003e\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDynesys\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e20.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eDTL\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e79.5\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbbreviations:\u003c/strong\u003e DTL, Dynesys Top-Loading system; SD, standard deviation\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab2\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePostoperative ROM at the index level and across the whole lumbar spine\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eTime point\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eROM of index level (\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eROM of whole L-spine (\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eROM loss of index level (\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eROM loss of whole L-spine (\u0026deg;)\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePre-op\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e14.8\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e29.38\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.21\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e16.33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e12.75\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 3 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.40\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e19.60\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.08\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 6 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e4.68\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e22.70\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e8.75\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e3.45\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 12 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.72\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e23.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e9.56\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e5.49\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e3.59\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e26.06\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e10.79\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.25\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 60 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e2.63\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e25.54\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e11.49\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e4.80\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cdiv class=\"gridtable\"\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\n \u003cp\u003e\u003cstrong\u003eAbbreviations:\u0026nbsp;\u003c/strong\u003eL-spine, lumbar spine; Pre-op, preoperative; Post-op, postoperative; ROM, range of motion\u003c/p\u003e\n \u003c/div\u003e\n \u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n \u003ctable id=\"Tab3\" border=\"1\"\u003e\n \u003ccaption\u003e\n \u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n \u003cdiv class=\"CaptionContent\"\u003e\n \u003cp\u003ePost-operative ROM preservation ratio compared to preoperative ROM\u003c/p\u003e\n \u003c/div\u003e\n \u003c/caption\u003e\n \u003cthead\u003e\n \u003ctr\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eFollow-up time point\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eIndex level (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003ep-value\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003eWhole L-spine (%)\u003c/p\u003e\n \u003c/th\u003e\n \u003cth align=\"left\"\u003e\n \u003cp\u003e\u003cem\u003ep-\u003c/em\u003evalue\u003c/p\u003e\n \u003c/th\u003e\n \u003c/tr\u003e\n \u003c/thead\u003e\n \u003ctbody\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 1 month\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e33\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.198\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e73\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e*0.026\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 3 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e41\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.122\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e78\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.651\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 6 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e48\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003eN/A\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 12 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e35\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.428\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.586\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 24 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e28\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e*0.014\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e100\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.558\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003ctr\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003ePost-op 60 months\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e20\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e*\u0026lt;0.001\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"char\"\u003e\n \u003cp\u003e98\u003c/p\u003e\n \u003c/td\u003e\n \u003ctd align=\"left\"\u003e\n \u003cp\u003e0.474\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tbody\u003e\n \u003ctfoot\u003e\n \u003ctr\u003e\n \u003ctd colspan=\"5\"\u003e\n \u003cp\u003e\u003cem\u003e* p\u0026thinsp;\u0026lt;\u0026thinsp;0.05 indicates a statistically significant difference compared with postoperative 6 months (paired t-test).\u003c/em\u003e\u003c/p\u003e\n \u003cp\u003e\u003cstrong\u003eAbbreviations:\u0026nbsp;\u003c/strong\u003eN/A, not applicable; ROM, range of motion\u003c/p\u003e\n \u003c/td\u003e\n \u003c/tr\u003e\n \u003c/tfoot\u003e\n \u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eIn contrast, whole-spine ROM decreased immediately after surgery, with only 73% of motion preserved 1 month postoperatively. Mobility improved significantly over time, and at 6 months post-postoperatively, whole-spine ROM was well preserved. The follow-up extended beyond 5 years, and whole-spine ROM showed no significant decline, remaining well preserved. While overall spinal mobility was maintained, ROM at the index (operative) segment was not preserved at the 5-year follow-up evaluation (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). These findings suggest that the preserved ROM in non-operated segments reflects compensatory motion, as the operated level is unable to maintain its original mobility. Furthermore, ASD was evaluated in this study. When comparing patients with and without ASD, no significant differences in whole-spine ROM preservation were observed during postoperative follow-up. However, at the 5-year follow-up, segmental ROM preservation was 9% in patients with ASD (17 patients) and 27% in patients without ASD (27 patients), showing a statistically significant difference (p\u0026thinsp;=\u0026thinsp;0.003) (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e). No other postoperative time points showed significant differences.\u003c/p\u003e\n\u003cp\u003eIn the subgroup analysis, factors such as sex, age, number of operated levels, and whether a discectomy was performed were examined in relation to ROM preservation. Sex-based analysis revealed that female patients experienced a greater reduction in ROM than male patients. This difference reached statistical significance at 2 years postoperatively (p\u0026thinsp;=\u0026thinsp;0.023) and demonstrated a continued, although not statistically significant, trend at 5 years (p\u0026thinsp;=\u0026thinsp;0.071). In contrast, none of the other examined factors, including age, number of operated levels, or whether discectomy was performed, were significantly associated with ROM preservation or ASD occurrence (Fig.\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e4\u003c/span\u003e).\u003c/p\u003e"},{"header":"Discussion","content":"\u003cp\u003eLumbar spine disorders are common and represent complex pathologies associated with age-related degeneration. Degeneration typically involves various interrelated structures, including the intervertebral discs, vertebral bodies with osteophyte formation, and thickening of the surrounding ligaments, ultimately leading to spinal stenosis or spondylolisthesis. In the early stages of symptom development, patients often respond well to medical therapy and conservative physical treatments. However, in advanced stages characterized by severe neural compression or progressive structural deformity, surgical intervention may be required. The primary objectives of spinal surgery are adequate neural decompression and preservation of spinal stability. When the underlying pathology can be resolved through decompression without compromising anatomical stability, less invasive procedures such as discectomy or laminectomy may suffice. However, when the symptoms of a patient are associated with compromised structural stability, or when decompression alone may induce postoperative instability, various devices or implants may be required to achieve adequate decompression while preserving stability [\u003cspan citationid=\"CR11\" class=\"CitationRef\"\u003e11\u003c/span\u003e]. Spinal fusion remains a conventional treatment approach for patients with structural deformity, preoperative instability, or a high risk of postoperative iatrogenic instability. Nevertheless, fusion is associated with several potential limitations, including ASD caused by loss of motion at the fused levels, pseudoarthrosis, infection, and implant failure [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. The primary concern is that rigid instrumentation and fusion increase mechanical stress on adjacent segments, potentially leading to degenerative changes at motion levels caudal or cephalad to the fused segment [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e]. In response to the limitations of spinal fusion, several devices and implants have been developed to mitigate ASD after fusion while preserving the required postoperative stability. These devices include artificial disc replacements and dynamic stabilization systems implanted during posterior procedures [\u003cspan additionalcitationids=\"CR13 CR14 CR15\" citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e16\u003c/span\u003e]. Since Roy-Camille and Saillant first introduced posterior fusion with transpedicular screws in 1984, this technique has been widely used in spine surgery because of its ability to provide immediate segmental stability. Therefore, most motion-preserving devices are based on posterior, non-fusion pedicle screw-based stabilization. The Graft ligament, the first instrument of these devices introduced in the 1990s, has theoretical limitations, including the potential to increase lateral recess and foraminal narrowing, ultimately increasing the risk of nerve root compression. Additionally, studies report unfavorable outcomes, leading to recommendations against the use of this procedure [\u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e6\u003c/span\u003e, \u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR17\" class=\"CitationRef\"\u003e17\u003c/span\u003e]. Dynesys, a posterior non-fusion spinal stabilization system developed by Dubois et al. [\u003cspan citationid=\"CR18\" class=\"CitationRef\"\u003e18\u003c/span\u003e] in 1991, was clinically introduced in 1994. During flexion, motion is regulated by tension to the cord, while during extension, the cylindrical polymer spacers function as partially compressible elements, allowing limited extension. Theoretically, this design reduces disc loading, thereby preventing the posterior annular compression associated with Graft ligamentoplasty [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e, \u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e19\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eSince its introduction, Dynesys has been widely used in spine surgery as a motion-preserving system. Most studies report that Dynesys provides clinical outcomes comparable to\u0026mdash;or, in some cases, better than\u0026mdash;those achieved with traditional posterior fusion. The system demonstrates advantages in certain domains, including preserving segmental ROM, reduced operative time and blood loss, shorter length of hospital stays, lower rates of ASD, and fewer complications [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e, \u003cspan citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eZhou et al. conducted a meta-analysis of 17 studies involving 1,296 patients, showing that Dynesys produces significantly lower postoperative Visual Analogue Scale (VAS) scores for both low back and leg pain than the traditional fusion. Additionally, the Dynesys group demonstrated a lower rate of surgical revision than the fusion group. The ROM at the stabilized segments in the fusion group decreased significantly, while the ROM at the adjacent segments increased significantly compared to those of the Dynesys group [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e]. Similarly, Wang et al conducted a meta-analysis involving 17 studies, showing no significant differences between the Dynesys and fusion groups in the Oswestry Disability Index, VAS scores for leg or back pain, or L2\u0026ndash;S1 ROM. However, the operation time, intraoperative blood loss, length of hospital stays, and complication rates are significantly lower in the Dynesys group than in the fusion group. Furthermore, studies report additional benefits of Dynesys, particularly in reducing ASD and preserving ROM [\u003cspan citationid=\"CR12\" class=\"CitationRef\"\u003e12\u003c/span\u003e]. ASD is widely recognized as the most significant complication following spinal fusion surgery, and its likelihood increases with advancing age. Loss of ROM at the index level is a key factor related to ASD. Therefore, the primary focus of this study is to assess the long-term effectiveness of Dynesys in preserving ROM [\u003cspan citationid=\"CR9\" class=\"CitationRef\"\u003e9\u003c/span\u003e].\u003c/p\u003e \u003cp\u003eIn this study, whole-spine ROM initially declined after surgery but recovered and remained well preserved at the 5-year postoperative follow-up. Additionally, segmental ROM was well preserved and reached its highest value at 6 months after surgery. However, it gradually decreased over time, with a significant decline observed at the 5-year follow-up, with segmental ROM preservation reducing to \u0026lt;\u0026thinsp;20% of the preoperative value. These findings suggest that ROM in the operative segments continues to decrease over the long term after implantation of the Dynesys/DTL system. Additionally, ASD continued to develop during the long-term follow-up. At the 5-year postoperative assessment, ASD was more prevalent in the group demonstrating lower ROM preservation.\u003c/p\u003e \u003cp\u003eStudies [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e, \u003cspan additionalcitationids=\"CR21 CR22\" citationid=\"CR20\" class=\"CitationRef\"\u003e20\u003c/span\u003e\u0026ndash;\u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e23\u003c/span\u003e] show that dynamic stabilization systems produce good clinical outcomes, preserve ROM at the stabilized segments, and limit hypermobility at adjacent segments, thereby reducing the risk of ASD. However, these studies generally report a follow-up period of \u0026lt;\u0026thinsp;3 years. When follow-up extends beyond 5 years, more complications occur. For example, Zhang et al. [\u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e8\u003c/span\u003e] report that, at a minimum follow-up of 72 months, the upper adjacent segment demonstrates significantly increased ROM and decreased disc height compared to the preoperative values. Yeh et al. [\u003cspan citationid=\"CR24\" class=\"CitationRef\"\u003e24\u003c/span\u003e] report that patients undergoing Dynesys surgery exhibit a significant decrease in ROM and a higher incidence of facet joint degeneration or spontaneous fusion at the index level than those undergoing microdiscectomy. These results were observed over a mean follow-up period of 36\u0026thinsp;\u0026plusmn;\u0026thinsp;16.8 months. Furthermore, Chen et al [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e] investigated a cohort of patients who presented with asymptomatic ASD before undergoing Dynesys surgery. The study reports that progression to symptomatic ASD requiring reoperation occurs at a mean follow-up of 7.22 years, with overweight patients demonstrating the strongest correlation with symptom progression. These findings support our findings, indicating that Dynesys surgery provides initial benefits to patients. However, patients showed a significant decline in ROM and an increased susceptibility to ASD during long-term follow-up. The early benefits of the procedure may diminish over time, particularly in specific patient subgroups. However, this decline was not associated with factors such as prior discectomy or the use of multilevel instrumentation. Although the ability of the Dynesys/DTL system to preserve segmental ROM remains uncertain, the cohort demonstrated that 61.3% (27/44) of patients did not develop ASD within 5 years postoperatively. These findings suggest that the Dynesys/DTL systems may offer partial protection against, or delay in the progression of ASD. However, substantial long-term ROM reduction remains common, with a potential higher rate of ASD with extended follow-up [\u003cspan citationid=\"CR4\" class=\"CitationRef\"\u003e4\u003c/span\u003e]. Overall, while these systems may mitigate early degeneration, they are inadequate for maintaining long-term segmental motion or preventing ASD. In summary, although studies show that dynamic stabilization systems preserve ROM and reduce the risk of ASD, most are limited to short-term follow-up of only 2\u0026ndash;3 years. This study, consistent with previous studies, indicates that the Dynesys/DTL system generally does not maintain segmental ROM or prevent ASD beyond 5 years. Nonetheless, these findings do not entirely discredit the potential value of pedicle-based dynamic stabilizers. We hypothesize that the loss of motion preservation may relate to excessive inter-screw spacing. Based on the protocol of the manufacturer, screws are distracted with approximately 2 N of force before placement of a spacer of corresponding length. This force may produce an overly rigid construct, highlighting the potential need for refinements in sizing or design.\u003c/p\u003e \u003cp\u003eThis study has some limitations. First, as a retrospective case analysis, the study is prone to potential selection bias owing to incomplete or missing medical records, necessitating the exclusion of certain cases. Second, the relatively small sample size (n\u0026thinsp;=\u0026thinsp;44) limits the overall statistical power and may prevent the generalizability of the findings. Finally, imaging evaluations were performed manually, potentially introducing the risk of minor measurement deviations. Future studies could incorporate artificial intelligence\u0026ndash;assisted image analysis to enhance measurement accuracy and standardization, thereby minimizing potential errors.\u003c/p\u003e"},{"header":"Conclusion","content":"\u003cp\u003ePreserving physiological motion while maintaining spinal stability remains a fundamental goal in spine surgery. These findings suggest that the current Dynesys/DTL systems do not adequately achieve this balance. Over long-term follow-up, segmental fusion with progressive loss of ROM was frequently observed after Dynesys system implantation, and the occurrence of ASD became increasingly evident beyond 5 years postoperatively. These findings indicate that the Dynesys/DTL system may function as a semi-rigid fixation construct rather than as a truly dynamic stabilization device. This finding highlights the need for further biomechanical research and continued refinement of dynamic stabilization system designs.\u003c/p\u003e"},{"header":"Abbreviations","content":"\u003cdiv class=\"DefinitionList\"\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eDTL\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eDynesys Top Loading\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eASD\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eadjacent segment degeneration\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eROM\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003erange of motion\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eHIVD\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003eherniated intervertebral discs\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eMRI\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003emagnetic resonance imaging\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003cdiv class=\"DefinitionListEntry\"\u003e \u003cdiv class=\"Term\"\u003e\u003cb\u003eVAS\u003c/b\u003e\u003c/div\u003e \u003cdiv class=\"Description\"\u003e \u003cp\u003evisual analogue scale\u003c/p\u003e \u003c/div\u003e \u003c/div\u003e \u003c/div\u003e"},{"header":"Declarations","content":"\u003cp\u003e\u003cstrong\u003eEthics approval\u0026nbsp;\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research paper was approved by the Institutional Review Board of Cathay General Hospital, Taiwan (approval number: CGH-P112068). All procedures were conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived due to the retrospective design of the study.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eConsent for publication\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAvailability of data and materials\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAll data generated and analysed in this study are fully presented within the article and its tables/figures.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eCompeting interests\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eMeng-Hsuan Hsieh reports no conflict of interest.\u003c/p\u003e\n\u003cp\u003eKai-Chieh Chang reports no conflict of interest.\u003c/p\u003e\n\u003cp\u003eChih-Ta Huanga reports no conflict of interest.\u003c/p\u003e\n\u003cp\u003eCheng-Ta Hsieh reports no conflict of interest.\u003c/p\u003e\n\u003cp\u003eChih-Ju Chang reports no conflict of interest.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eFunding\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthor contributions\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eMeng-Hsuan Hsieh:\u0026nbsp;\u003c/strong\u003estudy design, data collection, data analysis and manuscript preparation;\u003cstrong\u003e\u0026nbsp;Kai-Chieh Chang:\u0026nbsp;\u003c/strong\u003einvestigation, data collection, and data analysis;\u003cstrong\u003e\u0026nbsp;Chih-Ta Huang:\u0026nbsp;\u003c/strong\u003einvestigation, data collection, and data analysis;\u003cstrong\u003e\u0026nbsp;Cheng-Ta Hsieh:\u0026nbsp;\u003c/strong\u003eclinical coordination and data checking;\u003cstrong\u003e\u0026nbsp;and Chih-Ju Chang:\u003c/strong\u003e study design, manuscript revision for intellectual content, and project supervision. All authors have read and approved the final version of the manuscript.\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAcknowledgements\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eNot applicable\u003c/p\u003e\n\u003cp\u003e\u003cstrong\u003eAuthors’ Information\u003c/strong\u003e\u003c/p\u003e\n\u003cp\u003eAcademic degrees and email addresses of all authors:\u003c/p\u003e\n\u003cp\u003eMeng-Hsuan Hsieh, MD: [email protected]\u003c/p\u003e\n\u003cp\u003eKai-Chieh Chang, MD: [email protected]\u003c/p\u003e\n\u003cp\u003eChih-Ta Huang, MD: [email protected]\u003c/p\u003e\n\u003cp\u003eCheng-Ta Hsieh, MD, PhD: [email protected]\u003c/p\u003e\n\u003cp\u003eChih-Ju Chang, MD, PhD: [email protected]\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\u003cli\u003e\u003cspan\u003ePeng BG, Gao CH. Is Dynesys dynamic stabilization system superior to posterior lumbar fusion in the treatment of lumbar degenerative diseases? World J Clin Cases. 2020;8:5496\u0026ndash;500.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eGao Q, Yang D, Yuan Z. Clinical observation of dynesys dynamic internal fixation system in the treatment of lumbar degenerative diseases. Panminerva Med. 2021.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSt-Pierre GH, Jack A, Siddiqui MM, Henderson RL, Nataraj A. Nonfusion does not prevent adjacent segment disease: Dynesys long-term outcomes with minimum five-year follow-up. Spine (Phila Pa 1976). 2016;41:265\u0026ndash;73.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eChen KJ, Lai CY, Chiu LT. Adjacent segment disease following Dynesys stabilization for lumbar disorders: a case series of mid- and long-term follow-ups. World J Clin Cases. 2021;9:10850\u0026ndash;60.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eStoll TM, Dubois G, Schwarzenbach O. The dynamic neutralization system for the spine: a multi-center study of a novel non-fusion system. Eur Spine J. 2002;11(2suppl 2):S170\u0026ndash;8.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAnand N, Baron EM. Role of dynesys as pedicle-based nonfusion stabilization for degenerative disc disorders. Adv Orthop. 2012;2012:218385.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eKhalif\u0026eacute; M, Devriese F, Ferrero E, Zadegan F, Ajavon L, Mazel C. Dynesys\u0026reg; dynamic stabilization outcomes in degenerative spine surgery. Acta Orthop Belg. 2021;87:795\u0026ndash;803.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eZhou LP, Zhang RJ, Wang JQ. Medium and long-term radiographic and clinical outcomes of Dynesys dynamic stabilization versus instrumented fusion for degenerative lumbar spine diseases. BMC Surg. 2023;23:46.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHsieh CT, Chang CJ, Su IC, Lin LY. Clinical experiences of dynamic stabilizers: Dynesys and Dynesys top loading system for lumbar spine degenerative disease. Kaohsiung J Med Sci. 2016;32:207\u0026ndash;15.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHilibrand AS, Robbins M. Adjacent segment degeneration and adjacent segment disease: the consequences of spinal fusion? Spine J 2004;4(suppl 6):S190\u0026ndash;194.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBothmann M, Kast E, Boldt GJ, Oberle J. Dynesys fixation for lumbar spine degeneration. Neurosurg Rev. 2008;31:189\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eWang H, Peng J, Zeng Q. Dynesys system vs posterior decompression and fusion for the treatment of lumbar degenerative diseases. Med (Baltim). 2020;99:e19784.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eBredin S, Demay O, Mensa C, Madi K, Ohl X. Posterolateral fusion versus Dynesys dynamic stabilization: retrospective study at a minimum 5.5years' follow-up. Orthop Traumatol Surg Res. 2017;103:1241\u0026ndash;4.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eAbi-Hanna D, Kerferd J, Phan K, Rao P, Mobbs R. Lumbar disk arthroplasty for degenerative disk disease: literature review. World Neurosurg. 2018;109:188\u0026ndash;96.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFay LY, Chang CC, Chang HK. A hybrid dynamic stabilization and fusion system in multilevel lumbar spondylosis. Neurospine. 2018;15:231\u0026ndash;41.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLiu YL, Yang H, Zhang M. [Short-term effect of Isobar dynamic stabilization system fixation combined with lumbar discectomy in patients with lumbar disc herniation]. Zhonghua Yi Xue Za Zhi. 2019;99:188\u0026ndash;92.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eMulholland RC. SenguptaDK. Rationale, principles and experimental evaluation of the concept of soft stabilization. Eur Spine J. 2002;11(2suppl 2):S198\u0026ndash;205.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFreudiger S, Dubois G, Lorrain M. Dynamic neutralisation of the lumbar spine confirmed on a new lumbar spine simulator in vitro. Arch Orthop Trauma Surg. 1999;119:127\u0026ndash;32.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eSchmoelz W, Huber JF, Nydegger T, Claes L, Wilke HJ. Influence of a dynamic stabilisation system on load bearing of a bridged disc: an in vitro study of intradiscal pressure. Eur Spine J. 2006;15:1276\u0026ndash;85.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eHu Y, Gu YJ, Xu RM, Zhou LJ, Ma WH. Short-term clinical observation of the Dynesys neutralization system for the treatment of degenerative disease of the lumbar vertebrae. Orthop Surg. 2011;3:167\u0026ndash;75.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYu SW, Yang SC, Ma CH, Wu CH, Yen CY, Tu YK. Comparison of Dynesys posterior stabilization and posterior lumbar interbody fusion for spinal stenosis L4L5. Acta Orthop Belg. 2012;78:230\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eFei H, Xu J, Wang S, Xie Y, Ji F, Xu Y. Comparison between posterior dynamic stabilization and posterior lumbar interbody fusion in the treatment of degenerative disc disease: a prospective cohort study. J Orthop Surg Res. 2015;10:87.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eLi HP, Li F, Guan K, Zhao GM, Shan JL, Sun TS. Dynesys dynamic stabilization system for the lumbar degenerative disease: a preliminary report from China. Chin Med J. 2013;126:4265\u0026ndash;9.\u003c/span\u003e\u003c/li\u003e \u003cli\u003e\u003cspan\u003eYeh MY, Kuo CH, Wu JC. Changes of facet joints after dynamic stabilization: continuous degeneration or slow fusion? World Neurosurg. 2018;113:e45\u0026ndash;50.\u003c/span\u003e\u003c/li\u003e\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"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":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Lumbar Vertebrae, Range of Motion, Articular, Internal Fixators, Intervertebral Disc Degeneration, Spinal Diseases","lastPublishedDoi":"10.21203/rs.3.rs-8943008/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8943008/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003ch2\u003eBackground\u003c/h2\u003e \u003cp\u003eDynamic stabilization systems, such as Dynesys/Dynesys Top Loading (DTL), are developed to preserve segmental motion and mitigate adjacent segment degeneration (ASD) as alternatives to spinal fusion. However, long-term evidence supporting their effectiveness in maintaining a range of motion (ROM) remains limited.\u003c/p\u003e\u003ch2\u003eMethods\u003c/h2\u003e \u003cp\u003eIn this retrospective study, 44 patients undergoing lumbar dynamic stabilization were evaluated using the Dynesys/DTL system, with \u0026ge;\u0026thinsp;5 years of follow-up. Radiographic assessments included dynamic flexion\u0026ndash;extension radiographs at different postoperative time points. Segmental and whole-spine ROM were measured, while the incidence of ASD was recorded.\u003c/p\u003e\u003ch2\u003eResults\u003c/h2\u003e \u003cp\u003eSegmental ROM partially recovered by 6 months (48% of baseline) but progressively declined, preserving only 28% at 2 years and 20% at 5 years (p\u0026thinsp;\u0026lt;\u0026thinsp;0.05). In contrast, whole-spine ROM remained well preserved throughout the follow-up period, suggesting compensatory motion at nonoperated levels. ASD developed in 17 patients (38.6%), who demonstrated significantly lower segmental ROM preservation at 5 years than those without ASD (9% vs. 27%, p\u0026thinsp;=\u0026thinsp;0.003). Among the factors analyzed, only sex exhibited a trend toward greater ROM loss, with female patients showing a greater decline.\u003c/p\u003e\u003ch2\u003eConclusion\u003c/h2\u003e \u003cp\u003eDespite achieving early motion preservation, Dynesys/DTL systems do not maintain segmental ROM beyond 5 years and do not consistently prevent ASD. These findings indicate that Dynesys/DTL may function more as a semi-rigid fixation construct than as a truly dynamic stabilization, highlighting the need for improved biomechanical design and further long-term studies.\u003c/p\u003e","manuscriptTitle":"Long-Term Radiographic Outcomes of Dynesys Dynamic Stabilization in Lumbar Degenerative Disease: A 5-Year Retrospective Cohort Study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-08 14:50:00","doi":"10.21203/rs.3.rs-8943008/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"909473c9-db97-4c65-a2d9-80613a5c0314","owner":[],"postedDate":"March 8th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-04-10T00:24:14+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-08 14:50:00","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8943008","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8943008","identity":"rs-8943008","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}