Abstract
To investigate the effect of the Anterior Controllable Antedisplacement and Fusion (ACAF) procedure on stress within the spinal cord, nerve roots, and dura mater for different subtypes of cervical ossification of the posterior longitudinal ligament (C-OPLL) during progressive anterior decompression. C2-C7 cervical spine and spinal cord models were constructed based on CT images. Three C-OPLL subtypes (central-plateau, central-beak, and right-beak) were modeled and subjected to simulated ACAF treatment. By simulating the anterior displacement of the vertebral ossification complex, we analyzed the static stress changes in gray matter, white matter, nerve roots and dura mater for different C-OPLL subtypes. During decompression, among the three C-OPLL subtypes, ACAF achieved the most significant spinal cord decompression in the central-plateau type, especially when the encroachment ratio was reduced from 60 to 30%. ACAF produced the greatest reduction in nerve-root and dural stress in the right-beak type of C-OPLL, especially when the encroachment ratio decreased from 60 to 40%. The decompression efficiency for the nerve roots in the right-beak type and for the dura mater in the central-plateau type plateaued when the encroachment ratio was reduced from 60 to 50% and from 40 to 30%, respectively. In the right-beak type of C-OPLL, asymmetric compression generated higher stresses on the ipsilateral side of the spinal cord complex. After continued gradual decompression, the stress values of the spinal complex gradually decreased in all three groups. Our model demonstrates that all three OPLL subtypes achieve effective decompression, although the degree of stress relief varies across anatomical sites (e.g., spinal cord versus nerve roots) in a subtype-specific manner. The model data suggest that as the residual encroachment ratio decreases to approximately 30%, the marginal benefit of further decompression in terms of stress reduction plateaus. It is important to emphasize that this value is solely a biomechanical observation derived from our model, and clinically acceptable thresholds must be determined by integrating the patient’s neurological status and surgical risks.
Data availability
The datasets generated during and analysed during the current study are available from the corresponding author on reasonable request.
References
Boody, B. S., Lendner, M. & Vaccaro, A. R. Ossification of the posterior longitudinal ligament in the cervical spine: A review. Int. Orthop. 43(4), 797–805. https://doi.org/10.1007/s00264-018-4106-5 (2019) (Epub 2019/4/1).
Kawaguchi, Y. et al. Ossification of the posterior longitudinal ligament in not only the cervicalspine, but also other spinal regions: Analysis using multidetector computedtomography of the whole spine. Spine (Phila Pa 1976) 38(23), E1477–E1482. https://doi.org/10.1097/BRS.0b013e3182a54f00 (2013) (Epub 2013/11/1).
Yu, H. et al. Comparative effectiveness and safety of anterior cervical corpectomy with fusion, laminoplasty, and laminectomy and instrumented fusion for ossification of the posterior longitudinal ligament: A systematic review and network meta-analysis. J. Invest. Surg. 35(3), 667–676. https://doi.org/10.1080/08941939.2020.1871535 (2022) (Epub 2022/3/1).
Sun, J. et al. Anterior controllable antidisplacement and fusion surgery for the treatment of multilevel severe ossification of the posterior longitudinal ligament with myelopathy: Preliminary clinical results of a novel technique. Eur. Spine J. 27(6), 1469–1478. https://doi.org/10.1007/s00586-017-5437-4 (2018) (Epub 2018/6/1).
Sun, K. et al. Surgical outcomes after anterior controllable antedisplacement and fusion compared with single open-door laminoplasty: Preliminary analysis of postoperative changes of spinal cord displacements on T2-weighted magnetic resonance imaging. World Neurosurg. 127, e288–e298. https://doi.org/10.1016/j.wneu.2019.03.108 (2019) (Epub 2019/7/1).
Yang, H. et al. Anterior controllable antedisplacement fusion as a choice for ossification of posterior longitudinal ligament and degenerative kyphosis and stenosis: Postoperative morphology of dura mater and probability analysis of epidural hematoma based on 63 patients. World Neurosurg. 121, e954–e961. https://doi.org/10.1016/j.wneu.2018.10.052 (2019) (Epub 2019/1/1).
Miao, J., Sun, J., Shi, J., Chen, Y. & Chen, D. A novel anterior revision surgery for the treatment of cervical ossification of posterior longitudinal ligament: Case report and review of the literature. World Neurosurg. 113, 212–216. https://doi.org/10.1016/j.wneu.2018.02.076 (2018) (Epub 2018/5/1).
Li, S. et al. Comparison of the surgeries for the ossification of the posterior longitudinal ligament-related cervical spondylosis: A PRISMA-compliant network meta-analysis and literature review. Medicine (Baltimore) 100(9), e24900. https://doi.org/10.1097/MD.0000000000024900 (2021) (Epub 2021/3/5).
Mo, Z. J. et al. Biomechanical effects of cervical arthroplasty with U-shaped disc implant on segmental range of motion and loading of surrounding soft tissue. Eur. Spine J. 23(3), 613–621. https://doi.org/10.1007/s00586-013-3070-4 (2014) (Epub 2014/3/1).
Kameyama, T., Hashizume, Y. & Sobue, G. Morphologic features of the normal human cadaveric spinal cord. Spine (Phila Pa 1976) 21(11), 1285–1290. https://doi.org/10.1097/00007632-199606010-00001 (1996) (Epub 1996/6/1).
Xue, F. et al. Effects of cervical rotatory manipulation on the cervical spinal cord complexwith ossification of the posterior longitudinal ligament in the vertebral canal:A finite element study. Front. Bioeng. Biotechnol. 11, 1095587. https://doi.org/10.3389/fbioe.2023.1095587 (2023).
Matsunaga, S. et al. Radiographic predictors for the development of myelopathy in patients with ossification of the posterior longitudinal ligament: A multicenter cohort study. Spine (Phila Pa 1976) 33(24), 2648–2650. https://doi.org/10.1097/BRS.0b013e31817f988c (2008).
L, Y., L, J., W, F., W, L. & S, Y. Influence of K-line on intraoperative and hidden blood loss in patients with ossification of the posterior longitudinal ligament when undergoing unilateral open-door laminoplasty. J. Orthop. Surg. Res. 16(1), 34. https://doi.org/10.1186/s13018-020-02181-9 (2021).
Boruah, S. et al. Influence of bone microstructure on the mechanical properties of skull corticalbone - A combined experimental and computational approach. J. Mech. Behav. Biomed. Mater. 65, 688–704. https://doi.org/10.1016/j.jmbbm.2016.09.041 (2017).
Bevill, G., Easley, S. K. & Keaveny, T. M. Side-artifact errors in yield strength and elastic modulus for human trabecularbone and their dependence on bone volume fraction and anatomic site. J. Biomech. 40(15), 3381–3388. https://doi.org/10.1016/j.jbiomech.2007.05.008 (2007).
Liu, J. F., Shim, V. P. W., Lee, P.V.S. Quasi-static compressive and tensile tests on cancellous bone in human cervical spine. (ed. Prorok, B.C., Barthelat. F., Korach. C.S., Grande-Allen, K.J., Lipke, E., Lykofatitits, G. et al.) 109–118 (Springer, New York, 2013).
Kato, Y. et al. Biomechanical study of the effect of degree of static compression of the spinalcord in ossification of the posterior longitudinal ligament. J. Neurosurg. Spine. 12(3), 301–305. https://doi.org/10.3171/2009.9.SPINE09314 (2010).
Salvador, C. A. F., Maia, E. L., Costa, F. H., Escobar, J. D. & Oliveira, J. P. A compilation of experimental data on the mechanical properties and microstructural features of Ti-alloys. Sci. Data. 9(1), 188 (2022).
Nikonovich, M., Costa, J. F. S., Fonseca, A. C., Ramalho, A. & Emami, N. Structural, thermal, and mechanical characterisation of PEEK-based composites in cryogenic temperature. Polym. Test. 125, 108139. https://doi.org/10.1016/j.polymertesting.2023.108139 (2023).
Hasler, E. M., Herzog, W., Wu, J. Z., Müller, W. & Wyss, U. Articular cartilage biomechanics: theoretical models, material properties, andbiosynthetic response. Crit. Rev. Biomed. Eng. 27(6), 415–488 (1999) (Epub 1999/1/19).
Ichihara, K. et al. Gray matter of the bovine cervical spinal cord is mechanically more rigid and fragile than the white matter. J. Neurotrauma. 18(3), 361–367. https://doi.org/10.1089/08977150151071053 (2001).
Persson, C., Evans, S., Marsh, R., Summers, J. L. & Hall, R. M. Poisson’s ratio and strain rate dependency of the constitutive behavior of spinaldura mater. Ann. Biomed. Eng. 38(3), 975–983. https://doi.org/10.1007/s10439-010-9924-6 (2010) (Epub 2010/3/1).
Nishida, N. et al. Mechanical properties of nerve roots and rami radiculares isolated from fresh pigspinal cords. Neural Regen. Res. 10(11), 1869–1873. https://doi.org/10.4103/1673-5374.170319 (2015) (Epub 2015/11/1).
Cheng, S., Tan, K. & Bilston, L. E. The effects of the interthalamic adhesion position on cerebrospinal fluiddynamics in the cerebral ventricles. J. Biomech. 43(3), 579–582. https://doi.org/10.1016/j.jbiomech.2009.10.002 (2010) (Epub 2010/2/10).
Polak, K., Czyż, M., Ścigała, K., Jarmundowicz, W. & Będziński, R. Biomechanical characteristics of the porcine denticulate ligament in differentvertebral levels of the cervical spine-preliminary results of an experimentalstudy. J. Mech. Behav. Biomed. Mater. 34, 165–170. https://doi.org/10.1016/j.jmbbm.2014.02.010 (2014) (Epub 2014/6/1).
Kong, Q. J. et al. New anterior controllable antedisplacement and fusion surgery for cervicalossification of the posterior longitudinal ligament: A biomechanical study. J. Neurosurg. Spine https://doi.org/10.3171/2021.8.SPINE21879 (2022).
Hung, T. K., Lin, H. S., Bunegin, L. & Albin, M. S. Mechanical and neurological response of cat spinal cord under static loading. Surg. Neurol. 17(3), 213–217. https://doi.org/10.1016/0090-3019(82)90284-1 (1982) (Epub 1982/3/1).
Stoner, K. E., Abode-Iyamah, K. O., Magnotta, V. A., Howard, M. A. & Grosland, N. M. Measurement of in vivo spinal cord displacement and strain fields of healthy andmyelopathic cervical spinal cord. J. Neurosurg. Spine 31(1), 53–59. https://doi.org/10.3171/2018.12.SPINE18989 (2019) (Epub 2019/3/22).
Luo, X. et al. Anterior controllable antedisplacement and fusion (ACAF) technique for thetreatment of multilevel cervical spondylotic myelopathy with spinal stenosis(MCSMSS): A retrospective study of 54 cases. Clin. Spine Surg. 34(9), 322–330. https://doi.org/10.1097/BSD.0000000000001144 (2021) (Epub 2021/11/1).
Sa, R. Normal anatomy of the spinal cord. Pract. Neurol. 12(6), 367–370. https://doi.org/10.1136/practneurol-2012-000247 (2012).
Lee, J., Satkunendrarajah, K. & Fehlings, M. G. Development and characterization of a novel rat model of cervical spondyloticmyelopathy: The impact of chronic cord compression on clinical, neuroanatomical,and neurophysiological outcomes. J. Neurotrauma 29(5), 1012–1027. https://doi.org/10.1089/neu.2010.1709 (2012) (Epub 2012/3/20).
Khuyagbaatar, B., Kim, K., Park, W. M. & Kim, Y. H. Influence of sagittal and axial types of ossification of posterior longitudinalligament on mechanical stress in cervical spinal cord: A finite element analysis. Clin Biomech (Bristol, Avon) 30(10), 1133–1139. https://doi.org/10.1016/j.clinbiomech.2015.08.013 (2015) (Epub 2015/12/1).
He, Q. et al. Comparison of anterior vs. posterior surgery for cervical myelopathy due to OPLL: A systematic review and meta-analysis. Ann Med Surg (Lond) 86(11), 6653–6664. https://doi.org/10.1097/MS9.0000000000002556 (2024) (Epub 2024/11/1).
Sun, N., Jiang, C. & Liu, Y. Surgical options for ossification of the posterior longitudinal ligament of thecervical spine: A narrative review. J. Orthop. Surg. Res. 19(1), 707. https://doi.org/10.1186/s13018-024-05215-8 (2024) (Epub 2024/11/1).
Khuyagbaatar, B., Kim, K., Purevsuren, T., Lee, S. H. & Kim, Y. H. Biomechanical effects on cervical spinal cord and nerve root FollowingLaminoplasty for ossification of the posterior longitudinal ligament in theCervical spine: A comparison between Open-door and Double-door laminoplasty UsingFinite element analysis. J. Biomech. Eng. https://doi.org/10.1115/1.4039826 (2018) (Epub 2018/7/1).
Stoner, K. E. et al. A comprehensive finite element model of surgical treatment for cervicalmyelopathy. Clin Biomech (Bristol, Avon) 74, 79–86. https://doi.org/10.1016/j.clinbiomech.2020.02.009 (2020) (Epub 2020/4/1).
Sim, O., Ryu, D., Lee, J. & Lee, C. Stress distribution on spinal cord according to type of laminectomy for LargeFocal cervical ossification of posterior longitudinal ligament based on FiniteElement method. Bioengineering https://doi.org/10.3390/bioengineering9100519 (2022) (Epub 2022/10/2).
Nishida, N. et al. Effect of posterior decompression with and without fixation on a kyphoticcervical spine with ossification of the posterior longitudinal ligament. Spinal Cord 61(2), 133–138. https://doi.org/10.1038/s41393-022-00857-z (2023) (Epub 2023/2/1).
Park, M., Park, J. P., Kim, S. H. & Cha, Y. J. Evaluation of dural channels in the human parasagittal dural space and dura mater. Ann Anat. Anat. Anz. 244, 151974 (2022).
Palomeque-Del-Cerro, L. et al. A systematic review of the Soft-tissue connections between neck muscles and DuraMater: The myodural bridge. Spine (Phila Pa 1976) 42(1), 49–54. https://doi.org/10.1097/BRS.0000000000001655 (2017) (Epub 2017/1/1).
Panzer, M. B., Myers, B. S., Capehart, B. P. & Bass, C. R. Development of a finite element model for blast brain injury and the effects ofCSF cavitation. Ann. Biomed. Eng. 40(7), 1530–1544. https://doi.org/10.1007/s10439-012-0519-2 (2012) (Epub 2012/7/1).
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We would like to thank the editors and reviewers of this journal for their work on this study.
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This work was supported by the Ningxia Natural Science Foundation Project (grant 2023AAC03543).
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Xiao Zhang and Wenbo Gu contributed equally to this work. Xiao Zhang, Wenbo Gu and Haifeng Yuan were responsible for the overall design of the study, processing of bioinformatics data, and writing of the manuscript. Donghui Cao, Xusheng Li, Hongyang Zhao, Yu Yang and Xi Zhu were responsible for data analysis and figure preparation. All authors read and approved the final manuscript.
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Zhang, X., Gu, W., Cao, D. et al. Biomechanical investigation of spinal cord stress changes following ACAF for different subtypes of cervical OPLL. Sci Rep (2026). https://doi.org/10.1038/s41598-026-43810-3
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DOI: https://doi.org/10.1038/s41598-026-43810-3
