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<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Bioeng. Biotechnol.</journal-id>
<journal-title>Frontiers in Bioengineering and Biotechnology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Bioeng. Biotechnol.</abbrev-journal-title>
<issn pub-type="epub">2296-4185</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
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<article-meta>
<article-id pub-id-type="publisher-id">1606709</article-id>
<article-id pub-id-type="doi">10.3389/fbioe.2025.1606709</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Bioengineering and Biotechnology</subject>
<subj-group>
<subject>Original Research</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Biomechanical evaluation of percutaneous cement discoplasty combined with percutaneous vertebroplasty: a finite element analysis</article-title>
<alt-title alt-title-type="left-running-head">Zhou et al.</alt-title>
<alt-title alt-title-type="right-running-head">
<ext-link ext-link-type="uri" xlink:href="https://doi.org/10.3389/fbioe.2025.1606709">10.3389/fbioe.2025.1606709</ext-link>
</alt-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Zhou</surname>
<given-names>Xu</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>&#x2020;</sup>
</xref>
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<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Qin</surname>
<given-names>Shenghua</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="author-notes" rid="fn001">
<sup>&#x2020;</sup>
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<contrib contrib-type="author">
<name>
<surname>Huang</surname>
<given-names>Chunhai</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
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<contrib contrib-type="author">
<name>
<surname>Li</surname>
<given-names>Feiwen</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
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<contrib contrib-type="author">
<name>
<surname>Liu</surname>
<given-names>Jin</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
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<contrib contrib-type="author">
<name>
<surname>Wu</surname>
<given-names>Ti</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
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<contrib contrib-type="author" corresp="yes">
<name>
<surname>Zhang</surname>
<given-names>Mingzheng</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
<xref ref-type="corresp" rid="c001">&#x2a;</xref>
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<aff id="aff1">
<sup>1</sup>
<institution>Department of Orthopaedics</institution>, <institution>The First Affiliated Hospital of Jishou University</institution>, <institution>Jishou University</institution>, <addr-line>Jishou</addr-line>, <country>China</country>
</aff>
<aff id="aff2">
<sup>2</sup>
<institution>School of Medicine</institution>, <institution>Jishou University</institution>, <addr-line>Jishou</addr-line>, <country>China</country>
</aff>
<author-notes>
<fn fn-type="edited-by">
<p>
<bold>Edited by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/418863/overview">Alexandros E. Tsouknidas</ext-link>, Boston University, United States</p>
</fn>
<fn fn-type="edited-by">
<p>
<bold>Reviewed by:</bold> <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/669402/overview">Wenxin Niu</ext-link>, Tongji University, China</p>
<p>
<ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/2524023/overview">Konstantinos Krommydas</ext-link>, University of Western Macedonia, Greece</p>
</fn>
<corresp id="c001">&#x2a;Correspondence: Mingzheng Zhang, <email>zhangmingzheng@jsu.edu.cn</email>
</corresp>
<fn fn-type="equal" id="fn001">
<label>
<sup>&#x2020;</sup>
</label>
<p>These authors share first authorship</p>
</fn>
</author-notes>
<pub-date pub-type="epub">
<day>08</day>
<month>07</month>
<year>2025</year>
</pub-date>
<pub-date pub-type="collection">
<year>2025</year>
</pub-date>
<volume>13</volume>
<elocation-id>1606709</elocation-id>
<history>
<date date-type="received">
<day>06</day>
<month>04</month>
<year>2025</year>
</date>
<date date-type="accepted">
<day>26</day>
<month>06</month>
<year>2025</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#xa9; 2025 Zhou, Qin, Huang, Li, Liu, Wu and Zhang.</copyright-statement>
<copyright-year>2025</copyright-year>
<copyright-holder>Zhou, Qin, Huang, Li, Liu, Wu and Zhang</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/">
<p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p>
</license>
</permissions>
<abstract>
<sec>
<title>Introduction</title>
<p>Since the introduction of percutaneous cement discoplasty (PCD), numerous studies have confirmed its clinical efficacy in elderly patients. However, PCD is also associated with risks such as bone cement leakage and vertebral fractures. The purpose of this study was to present a biomechanical evaluation of two modified versions of PCD performed in combination with percutaneous vertebroplasty (PVP).</p>
</sec>
<sec>
<title>Methods</title>
<p>Data from a CT scan of a healthy male&#x2019;s lumbosacral region were used to establish finite element (FE) models of nonsurgical treatment, PCD, L4/5PCD &#x2b; L4L5PVP (modified technique 1, where the bone cement in the L4/5 disc space does not connect with the L4 and L5 vertebrae) and PCIF (modified technique 2, where the bone cement in the L4/5 disc space connects with the L4 and L5 vertebrae). A compressive of preload 150&#xa0;N and a moment of 10&#xa0;N&#xb7;m were applied to recreate flexion, extension, lateral bending, and axial rotation. The range of motion (ROM) of L3/4 and L4/5, maximum stress on the L3 inferior endplate, L4 inferior endplate and L5 superior endplate, stress on the annulus fibrosus of L4/5, and displacement of the bone cement were evaluated.</p>
</sec>
<sec>
<title>Results</title>
<p>Both modified techniques outperformed the simple PCD technique in reducing stress on the endplate, stress on the annulus fibrosus, and displacement of the bone cement. The L4/5PCD &#x2b; L4L5PVP technique was more advantageous in terms of reducing the incidence of postoperative complications. The addition of the PVP technique significantly enhanced spinal stability by increasing support to adjacent vertebrae, thereby reducing the risk of postoperative endplate fractures and bone cement leakage.</p>
</sec>
<sec>
<title>Conclusion</title>
<p>Modified PCD combined with PVP may be a safer and more effective option for treating degenerative disc diseases, providing important references for clinical treatment.</p>
</sec>
</abstract>
<kwd-group>
<kwd>spinal degeneration</kwd>
<kwd>biomechanics</kwd>
<kwd>finite element analysis</kwd>
<kwd>percutaneous cement discoplasty</kwd>
<kwd>percutaneous vertebroplasty</kwd>
</kwd-group>
<custom-meta-wrap>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Biomechanics</meta-value>
</custom-meta>
</custom-meta-wrap>
</article-meta>
</front>
<body>
<sec id="s1">
<title>1 Introduction</title>
<p>With the aging of society, the incidence of spinal degenerative diseases continues to increase. Degenerative disc diseases cause spinal instability which leads to severe back pain and radiating leg pain, significantly diminishing patients&#x2019; quality of life and increasing the economic burden on families and society (<xref ref-type="bibr" rid="B8">GBD 2015 Disease and Injury Incidence and Prevalence Collaborators, 2016</xref>). Conservative treatments have limited efficacy, and traditional open surgeries are often associated with high rates of complications, such as wound infections (<xref ref-type="bibr" rid="B18">Mihailidis et al., 2017</xref>). There is an urgent need for new and safe minimally invasive surgical treatments. In 2015, Varga et al. (<xref ref-type="bibr" rid="B25">Varga et al., 2015</xref>) were first to report the effectiveness and safety of percutaneous cement discoplasty (PCD) for patients with intractable mechanical back pain and vacuum disc phenomena. This technique involves injecting bone cement into the nucleus of the degenerated disc to maintain the disc height and achieve indirect foraminal decompression, showing promising clinical results (<xref ref-type="bibr" rid="B14">Kiss et al., 2019</xref>; <xref ref-type="bibr" rid="B2">Camino et al., 2020</xref>). However, because bone cement cannot effectively fuse with the endplate cartilage and has a high elastic modulus, there are risks of postoperative complications such as endplate fractures, implant displacement, and adjacent vertebral fractures (<xref ref-type="bibr" rid="B16">Li et al., 2022</xref>; <xref ref-type="bibr" rid="B10">Grewal et al., 2024</xref>), which can exacerbate patients&#x2019; back and leg pain. These issues may stem from insufficient strength of adjacent vertebrae, lumbar instability, and displacement of bone cement within the disc space. Therefore, enhancing the strength of adjacent vertebrae, improving lumbar stability, and securing the bone cement within the disc space are crucial. Hence, we propose performing percutaneous vertebroplasty (PVP) of the adjacent vertebrae above and below the PCD. To achieve this, we propose two modified techniques: technique 1 (L4/5PCD &#x2b; L4L5PVP, where the bone cement in the L4/5 disc space does not connect with the L4 and L5 vertebrae) or technique 2 (PCIF, where the bone cement in the L4/5 disc space connects with the L4 and L5 vertebrae) to promote fusion of the adjacent spinal motion segments (<xref ref-type="bibr" rid="B27">Xue et al., 2021</xref>). These modified techniques aim to reduce the risk of postoperative adjacent vertebral fractures and ensure stable anchoring of the bone cement within the disc space, minimizing the risks of displacement and PCD-related complications, providing a more effective and personalized surgical option for treating degenerative disc diseases and improving patients&#x2019; quality of life.</p>
</sec>
<sec sec-type="methods" id="s2">
<title>2 Methods</title>
<sec id="s2-1">
<title>2.1 Establishment of the nonsurgical finite element model</title>
<p>CT of a healthy male&#x2019;s lumbosacral region was performed with a slice thickness of 0.63&#xa0;mm and a resolution of 0.39 mm &#xd7; 0.39 mm, resulting in 776 DICOM format images. The lumbar CT images were imported into Mimics 10.01 (Materialise, Belgium) for vertebral segmentation and 3D geometric model reconstruction and exported in STL format. The STL-formatted vertebral models were imported into Geomagics Studio 12.0 (Raindrop Geomagics, Inc., U.S.) for smoothing and surface generation, producing NURBS surfaces, which were exported in IGS format. Since ligaments, such as the anterior longitudinal ligament (ALL), posterior longitudinal ligament (PLL), intertransverse ligament (TL), interspinous ligament (ISL), supraspinous ligament (SSL), capsular ligament (CL), and ligamentum flavum (LF) are not clearly visible in CT images, they were manually drawn as 3D lines in Mimics 10.01. Because the intervertebral disc is a soft tissue, it is difficult to segment from CT images, so it was drawn in CAD software Solidworks 2012 (Dassault Syst&#xe8;mes, France) in accordance with vertebral models and references, with the nucleus pulposus occupying 40% of the disc area (<xref ref-type="bibr" rid="B4">Chen et al., 2001</xref>). All the geometric models were imported into ABAQUS 6.11 (Simulia, Inc., USA) to establish the finite element model. The vertebrae consisted of the vertebral body and posterior elements, with the vertebral body further divided into cortical bone, cancellous bone, and the endplate. The cortical bone and endplate were modelled as 0.5&#xa0;mm thick shell elements, whereas the other bony structures and discs were modelled as solid elements. Ligaments were modelled as two-node truss elements. The material properties were sourced from the literature (<xref ref-type="bibr" rid="B24">Tsuang et al., 2009</xref>; <xref ref-type="bibr" rid="B7">Fan et al., 2010</xref>; <xref ref-type="bibr" rid="B1">Ambati et al., 2015</xref>; <xref ref-type="bibr" rid="B6">Ellingson et al., 2015</xref>; <xref ref-type="bibr" rid="B11">Guo et al., 2025</xref>) and are detailed in <xref ref-type="table" rid="T1">Table 1</xref>. The full lumbar finite element model included the L1&#x2013;L5 vertebrae, sacrum, and connecting discs and ligaments (<xref ref-type="fig" rid="F1">Figure 1a</xref>).</p>
<table-wrap id="T1" position="float">
<label>TABLE 1</label>
<caption>
<p>Material properties of the lumbar finite element model.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th align="left">Tissue type</th>
<th align="left">Young&#x2019;s modulus (MPa)</th>
<th align="left">Poisson&#x2019;s ratio</th>
<th align="left">Cross-sectional area (mm<sup>2</sup>)</th>
<th align="left">Abaqus section type</th>
<th align="left">Abaqus element type</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="left" colspan="6">Bony structure</td>
</tr>
<tr>
<td align="left">Cancellous bone</td>
<td align="left">100</td>
<td align="left">0.2</td>
<td align="left">-</td>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
<tr>
<td align="left">Cortical bone</td>
<td align="left">12,000</td>
<td align="left">0.3</td>
<td align="left">-</td>
<td align="left">Shell</td>
<td align="left">S3</td>
</tr>
<tr>
<td align="left">Posterior elements</td>
<td align="left">3500</td>
<td align="left">0.25</td>
<td align="left">-</td>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
<tr>
<td align="left">Endplates</td>
<td align="left">3000</td>
<td align="left">0.25</td>
<td align="left">-</td>
<td align="left">Shell</td>
<td align="left">S3</td>
</tr>
<tr>
<td align="left">Sacrum and coccyx</td>
<td align="left">3500</td>
<td align="left">0.25</td>
<td align="left"/>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
<tr>
<td align="left" colspan="6">Ligaments</td>
</tr>
<tr>
<td align="left">ALL</td>
<td align="left">15</td>
<td align="left">&#x2014;</td>
<td align="left">40</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">PLL</td>
<td align="left">10</td>
<td align="left">&#x2014;</td>
<td align="left">20</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">SSL</td>
<td align="left">8</td>
<td align="left">&#x2014;</td>
<td align="left">30</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">LF</td>
<td align="left">15</td>
<td align="left">&#x2014;</td>
<td align="left">40</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">ISL</td>
<td align="left">10</td>
<td align="left">&#x2014;</td>
<td align="left">40</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">TL</td>
<td align="left">10</td>
<td align="left">&#x2014;</td>
<td align="left">1.8</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left">CL</td>
<td align="left">7.5</td>
<td align="left">&#x2014;</td>
<td align="left">30</td>
<td align="left">Truss</td>
<td align="left">T3D2</td>
</tr>
<tr>
<td align="left" colspan="6">Intervertebral disc</td>
</tr>
<tr>
<td align="left">Nuclei pulposi</td>
<td align="left">1</td>
<td align="left">0.499</td>
<td align="left">&#x2014;</td>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
<tr>
<td align="left">Annuli fibrosi</td>
<td align="left">4.2</td>
<td align="left">0.45</td>
<td align="left">&#x2014;</td>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
<tr>
<td align="left">Bone cement</td>
<td align="left">3000</td>
<td align="left">0.3</td>
<td align="left">&#x2014;</td>
<td align="left">Solid</td>
<td align="left">C3D4</td>
</tr>
</tbody>
</table>
</table-wrap>
<fig id="F1" position="float">
<label>FIGURE 1</label>
<caption>
<p>FE models of nonsurgical and surgical lumbar-sacral spines. <bold>(A)</bold> Nonsurgical model; <bold>(B)</bold> L4/5 PCD model (only the L4/5 segment is shown); <bold>(C)</bold> L4/5 PCD &#x2b; L4L5 PVP model (only the L4/5 segment is shown); <bold>(D)</bold> PCIF model (only the L4/5 segment is shown).</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g001.tif">
<alt-text content-type="machine-generated">Image displaying four panels labeled (a) to (d). Panel (a) shows a green, textured 3D model of a spine segment. Panels (b), (c), and (d) depict translucent 3D models of vertebrae, each with slightly different structural features.</alt-text>
</graphic>
</fig>
</sec>
<sec id="s2-2">
<title>2.2 Establishment of the surgical finite element model</title>
<p>Three surgical models were established: the L4/5 PCD model (<xref ref-type="fig" rid="F1">Figure 1b</xref>), the modified technique 1 (L4/5PCD &#x2b; L4L5PVP) model (<xref ref-type="fig" rid="F1">Figure 1c</xref>), and the modified technique 2 (PCIF) model (<xref ref-type="fig" rid="F1">Figure 1d</xref>). For the PCD model, the nucleus pulposus in the L4-L5 segment was replaced with bone cement. L4/5PCD &#x2b; L4L5PVP: In addition to PCD, PVP was performed on the vertebrae above and below the affected disc. PCIF: After windows were created in the endplates above and below the affected disc, PCD was performed, followed by PVP on the adjacent vertebrae. Bone cement was modelled as a solid element with an elastic modulus of 3000&#xa0;MPa and a Poisson&#x2019;s ratio of 0.3.</p>
</sec>
<sec id="s2-3">
<title>2.3 Boundary conditions, model loading, and FE analysis</title>
<p>The facet joints were modelled as sliding friction with a coefficient of 0.1 (<xref ref-type="bibr" rid="B31">Zhong et al., 2009</xref>). The contacts between the endplate and vertebral body, the endplate and nucleus pulposus, the endplate and annulus fibrosus, and the bone cement and endplate/cancellous bone were set as tied. The sacrum was fully fixed to simulate the fixation method used in the biomechanical testing of cadaveric samples. A geometric reference point was selected at the centre of the L1 superior surface and coupled to the L1 surface for load application. A compressive preload of 150&#xa0;N and a moment of 10&#xa0;N&#xb7;m were applied to recreate flexion, extension, lateral bending, and axial rotation. The data were collected and analysed post calculation. The evaluation indicators included (1) the ROM of L3/4 and L4/5; (2) the maximum stress on the L3 inferior endplate; (3) the maximum stress on the L4 inferior endplate; (4) the maximum stress on the L5 superior endplate; (5) the maximum displacement of bone cement in the disc space; and (6) the maximum von Mises stress on the L4/5 annulus fibrosus.</p>
</sec>
</sec>
<sec sec-type="results" id="s3">
<title>3 Results</title>
<sec id="s3-1">
<title>3.1 FE mesh sensitivity analysis</title>
<p>The maximum von Mises stress on the L4/5 annulus fibrosus was used to perform a mesh sensitivity analysis of the model. The vertebrae of the nonsurgical model were meshed with mesh sizes ranging from 6&#xa0;mm to 1&#xa0;mm, and the results were shown in <xref ref-type="fig" rid="F2">Figure 2</xref>. In general, reducing the mesh size improved result accuracy due to enhanced numerical convergence. Under all four loading conditions, the discrepancy in results between the 2-mm and 1-mm meshes was within 5%. After balancing computational efficiency and precision, we ultimately adopted a 2-mm mesh size for the vertebral meshing. During the meshing process, mesh quality control parameters specified in <xref ref-type="table" rid="T2">Table 2</xref> were applied.</p>
<fig id="F2" position="float">
<label>FIGURE 2</label>
<caption>
<p>FE mesh sensitivity analysis.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g002.tif">
<alt-text content-type="machine-generated">Bar chart showing maximum von-Mises stress on the disc annulus at L4-L5 level in megapascals for different movements: flexion, extension, torsion, and lateral bending. Mesh sizes of 6mm, 5mm, 4mm, 3mm, 2mm, and 1mm are represented in different colors. Each movement shows varying stress levels across different mesh sizes, with stress values generally ranging from 0.4 to 0.9 MPa.</alt-text>
</graphic>
</fig>
<table-wrap id="T2" position="float">
<label>TABLE 2</label>
<caption>
<p>Quality control parameters of the FE meshes.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th align="center">Quality control parameters</th>
<th align="left">Quadrilateral element</th>
<th align="left">Triangular element</th>
<th align="left">Tetrahedral element</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td align="center">Aspect ratio</td>
<td align="center">&#x3c;5.0</td>
<td align="center">&#x3c;5.0</td>
<td align="center">&#x3c;5.0</td>
</tr>
<tr>
<td align="center">Jacobian ratio</td>
<td align="center">&#x3e;0.7</td>
<td align="center">&#x3e;0.7</td>
<td align="center">&#x3e;0.7</td>
</tr>
<tr>
<td align="center">Internal angles</td>
<td align="center">45&#xb0;&#x2013;135&#xb0;</td>
<td align="center">20&#xb0;&#x2013;120&#xb0;</td>
<td align="center">20&#xb0;&#x2013;120&#xb0;</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec id="s3-2">
<title>3.2 Model validation</title>
<p>To validate the model, the ROM of the L1-L5 vertebrae in the nonsurgical model was compared with that in previous <italic>in vitro</italic> experiments (<xref ref-type="bibr" rid="B29">Yamamoto et al., 1989</xref>; <xref ref-type="bibr" rid="B19">Panjabi et al., 1994</xref>) and computational models (<xref ref-type="bibr" rid="B4">Chen et al., 2001</xref>; <xref ref-type="bibr" rid="B5">Chen et al., 2012</xref>; <xref ref-type="bibr" rid="B23">Tsai et al., 2016</xref>). As shown in <xref ref-type="fig" rid="F3">Figure 3</xref>, the ROM of the L1&#x2013;L5 vertebrae in the nonsurgical model was 13.74&#xb0;, 14.70&#xb0;, 11.17&#xb0;, and 10.74&#xb0; during flexion, extension, lateral bending, and rotation, respectively, showing good consistency with previous results.</p>
<fig id="F3" position="float">
<label>FIGURE 3</label>
<caption>
<p>Model validation.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g003.tif">
<alt-text content-type="machine-generated">Bar chart comparing the range of motion (ROM) in degrees for flexion, extension, lateral bending, and torsion across different studies. Studies include Yamamoto (1989), Panjabi (1994), Chen (2001), Chen (2012), Tsai (2016), and the present study. Flexion shows the highest ROM, while torsion shows the lowest across all studies.</alt-text>
</graphic>
</fig>
</sec>
<sec id="s3-3">
<title>3.3 The ROM of the L3/4 and L4/5 segments</title>
<p>In the L4/5PCD model, the L3/4 segment had the lowest ROM in all loading conditions, with values of 1.80&#xb0; during flexion, 3.94&#xb0; during extension, 1.68&#xb0; during lateral bending, and 2.75&#xb0; during rotation. The ROM of the segments in all loading conditions was similar in the L4/5PCD &#x2b; L4L5PVP and PCIF models (<xref ref-type="fig" rid="F4">Figure 4a</xref>; <xref ref-type="table" rid="T3">Table 3</xref>). The ROM of the L4/5 segment in all loading conditions was greater in the L4/5PCD model than in the L4/5PCD &#x2b; L4L5PVP and PCIF models, with values of 1.38&#xb0; during flexion, 2.72&#xb0; during extension, 1.16&#xb0; during lateral bending, and 0.28&#xb0; during rotation (<xref ref-type="fig" rid="F4">Figure 4b</xref>; <xref ref-type="table" rid="T3">Table 3</xref>).</p>
<fig id="F4" position="float">
<label>FIGURE 4</label>
<caption>
<p>Range of motion. <bold>(A)</bold> Range of motion of the L3/4 segment; <bold>(B)</bold> Range of Motion of the L4/5 segment.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g004.tif">
<alt-text content-type="machine-generated">Bar charts labeled (a) and (b) compare the range of motion (ROM) in degrees for the L3/4 and L4/5 spine segments during flexion, extension, lateral bending, and torsion. Three conditions are represented: L4/5PCD, L4/5PCD+L4L5PVP, and PCIF, each indicated by different colored bars. Chart (a) shows data for the L3/4 segment, and chart (b) shows data for the L4/5 segment.</alt-text>
</graphic>
</fig>
<table-wrap id="T3" position="float">
<label>TABLE 3</label>
<caption>
<p>Analysis results comparison table.</p>
</caption>
<table>
<thead valign="top">
<tr>
<th rowspan="2" align="left">FE models</th>
<th rowspan="2" align="left">Loading conditions</th>
<th colspan="2" align="center">ROM (&#xb0;)</th>
<th colspan="4" align="center">Maximum von mises stress (MPa)</th>
<th rowspan="2" align="center">Bone cement displacement (mm)</th>
</tr>
<tr>
<th align="center">L3/4 segment</th>
<th align="center">L4/5 segment</th>
<th align="center">L3 inferior endplate</th>
<th align="center">L4 inferior endplate</th>
<th align="center">L5 superior endplate</th>
<th align="center">L4/5 annulus fibrosus</th>
</tr>
</thead>
<tbody valign="top">
<tr>
<td rowspan="4" align="left">L4/5 PCD</td>
<td align="left">Flexion</td>
<td align="center">1.80</td>
<td align="center">1.38</td>
<td align="center">30.90</td>
<td align="center">25.61</td>
<td align="center">20.50</td>
<td align="center">0.24</td>
<td align="center">2.71</td>
</tr>
<tr>
<td align="left">Extension</td>
<td align="center">3.94</td>
<td align="center">2.72</td>
<td align="center">54.82</td>
<td align="center">53.66</td>
<td align="center">46.96</td>
<td align="center">0.65</td>
<td align="center">4.64</td>
</tr>
<tr>
<td align="left">Lateral bending</td>
<td align="center">1.68</td>
<td align="center">1.16</td>
<td align="center">27.51</td>
<td align="center">26.59</td>
<td align="center">27.86</td>
<td align="center">0.33</td>
<td align="center">1.12</td>
</tr>
<tr>
<td align="left">Torsion</td>
<td align="center">2.75</td>
<td align="center">0.28</td>
<td align="center">16.17</td>
<td align="center">20.10</td>
<td align="center">23.13</td>
<td align="center">0.13</td>
<td align="center">4.53</td>
</tr>
<tr>
<td rowspan="4" align="left">L4/5 PCD &#x2b; L4L5 PVP</td>
<td align="left">Flexion</td>
<td align="center">2.54</td>
<td align="center">0.86</td>
<td align="center">29.41</td>
<td align="center">12.35</td>
<td align="center">14.18</td>
<td align="center">0.14</td>
<td align="center">1.81</td>
</tr>
<tr>
<td align="left">Extension</td>
<td align="center">4.46</td>
<td align="center">2.18</td>
<td align="center">47.76</td>
<td align="center">24.25</td>
<td align="center">29.32</td>
<td align="center">0.33</td>
<td align="center">1.82</td>
</tr>
<tr>
<td align="left">Lateral bending</td>
<td align="center">2.31</td>
<td align="center">0.80</td>
<td align="center">26.65</td>
<td align="center">15.31</td>
<td align="center">21.82</td>
<td align="center">0.22</td>
<td align="center">0.88</td>
</tr>
<tr>
<td align="left">Torsion</td>
<td align="center">2.77</td>
<td align="center">0.28</td>
<td align="center">15.79</td>
<td align="center">15.53</td>
<td align="center">18.62</td>
<td align="center">0.10</td>
<td align="center">0.86</td>
</tr>
<tr>
<td rowspan="4" align="left">PCIF</td>
<td align="left">Flexion</td>
<td align="center">2.60</td>
<td align="center">0.33</td>
<td align="center">30.60</td>
<td align="center">21.90</td>
<td align="center">20.76</td>
<td align="center">0.21</td>
<td align="center">2.54</td>
</tr>
<tr>
<td align="left">Extension</td>
<td align="center">5.05</td>
<td align="center">0.34</td>
<td align="center">51.67</td>
<td align="center">36.65</td>
<td align="center">44.16</td>
<td align="center">0.51</td>
<td align="center">4.70</td>
</tr>
<tr>
<td align="left">Lateral bending</td>
<td align="center">1.89</td>
<td align="center">0.84</td>
<td align="center">27.21</td>
<td align="center">23.23</td>
<td align="center">17.66</td>
<td align="center">0.27</td>
<td align="center">1.01</td>
</tr>
<tr>
<td align="left">Torsion</td>
<td align="center">2.76</td>
<td align="center">0.25</td>
<td align="center">16.48</td>
<td align="center">17.09</td>
<td align="center">19.42</td>
<td align="center">0.11</td>
<td align="center">1.60</td>
</tr>
</tbody>
</table>
</table-wrap>
</sec>
<sec id="s3-4">
<title>3.4 Maximum von mises stress on the endplates</title>
<p>The maximum von Mises stress on the L3 and L4 inferior endplates and the L5 superior endplate in all four loading conditions was lowest in the L4/5PCD &#x2b; L4L5PVP model; however, the von Mises stress on the L5 superior endplate during lateral bending was greater in the L4/5PCD &#x2b; L4L5PVP model than in the PCIF model. The differences between the L4/5PCD &#x2b; L4L5PVP and PCIF models were minimal (<xref ref-type="fig" rid="F5">Figures 5</xref>; <xref ref-type="table" rid="T3">Table 3</xref>).</p>
<fig id="F5" position="float">
<label>FIGURE 5</label>
<caption>
<p>Maximum von Mises stress values. <bold>(A)</bold> Maximum von Mises stress values on the inferior endplate of L3; <bold>(B)</bold> Maximum von Mises stress values on the inferior endplate of L4; <bold>(C)</bold> Maximum von Mises stress values on the superior endplate of L5.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g005.tif">
<alt-text content-type="machine-generated">Three bar graphs labeled (a), (b), and (c) compare maximum von Mises stress values (MPa) on L4 and L5 vertebral endplates for different movements: flexion, extension, lateral bending, and torsion. Each graph displays values for three conditions: L4/5PCD (blue), L4/5PCD+L4L5PVP (orange), and PCIF (gray). Graph (a) compares stresses on L4 inferior endplate, (b) on L4 superior endplate, and (c) on L5 superior endplate. All graphs show higher stresses during extension across all conditions.</alt-text>
</graphic>
</fig>
</sec>
<sec id="s3-5">
<title>3.5 Maximum von mises stress on the L4/5 annulus fibrosus</title>
<p>The maximum stress on the L4/5 annulus fibrosus in all four loading conditions was lower in both models than in the PCD model. L4/5PCD &#x2b; L4L5PVP resulted in the lowest stress, with 0.1399&#xa0;MPa during flexion, 0.6461&#xa0;MPa during extension, 0.3297&#xa0;MPa during lateral bending, and 0.1003&#xa0;MPa during rotation (<xref ref-type="fig" rid="F6">Figure 6</xref>; <xref ref-type="table" rid="T3">Table 3</xref>).</p>
<fig id="F6" position="float">
<label>FIGURE 6</label>
<caption>
<p>Maximum stress values on the annulus fibrosus of the L4/5 segment.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g006.tif">
<alt-text content-type="machine-generated">Bar chart showing maximum stress values on the annulus fibrosus of the L4/5 segment for flexion, extension, lateral bending, and torsion. Three categories: L4/5PCD (blue), L4/5PCD+L4L5PVP (red), and PCIF (green). Blue bars are highest in extension; green in lateral bending.</alt-text>
</graphic>
</fig>
</sec>
<sec id="s3-6">
<title>3.6 Bone cement displacement</title>
<p>The maximum displacement of bone cement in the disc space during flexion, extension, and lateral bending was similar in all four loading conditions in the L4/5PCD and PCIF models. However, PCIF significantly reduced displacement during rotation. L4/5PCD &#x2b; L4L5PVP resulted in the smallest displacement (<xref ref-type="fig" rid="F7">Figure 7</xref>; <xref ref-type="table" rid="T3">Table 3</xref>).</p>
<fig id="F7" position="float">
<label>FIGURE 7</label>
<caption>
<p>The maximum displacement of the bone cement.</p>
</caption>
<graphic xlink:href="fbioe-13-1606709-g007.tif">
<alt-text content-type="machine-generated">Bar chart showing maximum displacement of bone cement in millimeters across four movements: flexion, extension, lateral bending, and torsion. Three conditions represented: L4/5PCD, L4/5PCD+L4L5PVP, and PCIF. L4/5PCD has the highest displacement in extension and torsion. PCIF shows the greatest displacement in flexion, while L4/5PCD+L4L5PVP records the lowest in all categories.</alt-text>
</graphic>
</fig>
</sec>
</sec>
<sec sec-type="discussion" id="s4">
<title>4 Discussion</title>
<p>Since the introduction of PCD, numerous studies have explored its effectiveness (<xref ref-type="bibr" rid="B26">Willhuber et al., 2021</xref>; <xref ref-type="bibr" rid="B12">Jia et al., 2022</xref>; <xref ref-type="bibr" rid="B16">Li et al., 2022</xref>; <xref ref-type="bibr" rid="B21">Techens et al., 2022</xref>; <xref ref-type="bibr" rid="B30">Zhang et al., 2024</xref>) and subsequently confirmed its clinical efficacy in elderly patients with vacuum disc phenomena and lumbar instability. However, PCD is associated with risks such as bone cement leakage and vertebral fractures (<xref ref-type="bibr" rid="B14">Kiss et al., 2019</xref>; <xref ref-type="bibr" rid="B3">Camino-Willhuber et al., 2021</xref>; <xref ref-type="bibr" rid="B28">Yamada et al., 2021</xref>). After PCD, the bone cement acts as an independent disc spacer but cannot fully fuse with the endplate cartilage. The annulus fibrosus, which is often incomplete or weak, may be further damaged during surgery, increasing the risk of cement leakage and displacement, similar to cage displacement in lumbar fusion surgery. Instability and osteoporosis progression after PCD are significant factors contributing to cement displacement (<xref ref-type="bibr" rid="B13">Kimura et al., 2012</xref>; <xref ref-type="bibr" rid="B15">Lee et al., 2018</xref>; <xref ref-type="bibr" rid="B20">Park et al., 2019</xref>). PCD does not provide sufficient stability or achieve solid interbody fusion, making cement displacement a critical concern. In this study, L4/5PCD &#x2b; L4L5PVP resulted in the smallest degree of cement displacement, indicating its efficacy for securing the cement. The addition of the PVP technique enhances support to adjacent vertebrae, effectively securing the cement and reducing the risk of implant displacement.</p>
<p>
<xref ref-type="bibr" rid="B22">Techens et al. (2020)</xref> reported the stress concentration on the endplates adjacent to the PCD-treated discs in an <italic>in vitro</italic> biomechanical study, which was consistent with the stress concentration calculated in a sheep model examined by <xref ref-type="bibr" rid="B9">Ghandour et al. (2022)</xref>. To address the risk of adjacent endplate fractures, we compared the maximum stress on the L3 inferior endplate, L4 inferior endplate, and L5 superior endplate between PCD and the two modified techniques. Compared with PCD, both L4/5PCD &#x2b; L4L5PVP and PCIF reduced the maximum stress on the L3 inferior endplate, indicating that reinforcement provided by PVP does not increase the risk of adjacent vertebral fractures. This advantage stems from the ability of PVP to distribute stress, reduce the burden on the endplates and lower the risk of postoperative fractures.</p>
<p>The ROM of the L3/4 segment was the lowest in the L4/5PCD model, indicating the strongest restriction on spinal motion, likely due to the high elastic modulus of the disc after cement injection. The ROM of the L4/5 segment in the L4/5PCD model was higher, indicating limited improvement in stability. In contrast, L4/5PCD &#x2b; L4L5PVP and PCIF significantly reduced ROM, with PCIF providing the strongest stability as it fuses adjacent vertebrae and the cement in the affected disc space, reducing the risk of adjacent vertebral fractures and cement displacement. <xref ref-type="bibr" rid="B16">Li et al. (2022)</xref> also used finite element analysis to study PCD, confirming its impact on lumbar ROM and strength. The fusion of bone cement with endplates offers more biomechanical advantages, reducing the risk of cement subsidence and improving segmental stability.</p>
<p>The analysis of stress on the annulus fibrosus revealed that, compared with PCD, both L4/5PCD &#x2b; L4L5PVP and PCIF reduced the maximum stress on the L4&#x2012;5 annulus fibrosus in all motion directions, with L4/5PCD &#x2b; L4L5PVP showing the best results. This finding indicates that the addition of PVP led to effective stress distribution, reducing the burden on the annulus fibrosus and lowering the risk of postoperative annulus rupture.</p>
<p>Although the biomechanical effects of PCD and the two modified techniques were compared via finite element analysis, several limitations should be noted. For example, single subject CT images were used, thus limiting the generalizability of the results. A larger sample of patients of different sexes, ages, and weights should be selected for future studies to improve the applicability of the findings. In terms of model construction, simplified material parameters were used: the ligaments were modelled as two-node truss elements, while annulus fibrosi and endplates were modelled as isotropic linear elastic materials. The above simplifications may not accurately capture the complex kinematic characteristics of the spine. Muscular contributions were not incorporated in the simulation, and the study exclusively focused on static analyses without dynamic simulations. Subsequent studies ought to overcome these limitations by developing more refined models, such as utilizing three-dimensional solid ligaments with nonlinear properties to simulate ligaments and incorporating dynamic loading simulations to capture time-dependent behaviours. Furthermore, in future research, clinical follow-up data should be included to further validate the accuracy and reliability of the finite element analysis results.</p>
</sec>
<sec sec-type="conclusion" id="s5">
<title>5 Conclusion</title>
<p>In conclusion, both L4/5PCD &#x2b; L4L5PVP and PCIF outperformed PCD in reducing the maximum stress on the endplate, maximum stress on the annulus fibrosus, and maximum bone cement displacement. Compared with PCIF, L4/5PCD &#x2b; L4L5PVP was associated with fewer postoperative complications. The use of these techniques together enhance spinal stability by increasing support to adjacent vertebrae, which reduces the risk of postoperative complications. For patients with degenerative disc diseases, especially elderly patients, the combination of these techniques may be a safer and more effective treatment option, providing important references for clinical treatment.</p>
</sec>
</body>
<back>
<sec sec-type="data-availability" id="s6">
<title>Data availability statement</title>
<p>The raw data supporting the conclusion of this article will be made available by the authors, without undue reservation.</p>
</sec>
<sec sec-type="author-contributions" id="s7">
<title>Author contributions</title>
<p>XZ: Data curation, Formal Analysis, Funding acquisition, Investigation, Writing &#x2013; original draft. SQ: Data curation, Formal Analysis, Funding acquisition, Investigation, Validation, Writing &#x2013; original draft. CH: Data curation, Formal Analysis, Resources, Supervision, Writing &#x2013; review &#x26; editing. FL: Data curation, Formal Analysis, Resources, Supervision, Writing &#x2013; review &#x26; editing. JL: Formal Analysis, Software, Visualization, Writing &#x2013; review &#x26; editing. TW: Software, Visualization, Writing &#x2013; review &#x26; editing. MZ: Conceptualization, Funding acquisition, Methodology, Project administration, Software, Supervision, Validation, Writing &#x2013; review &#x26; editing.</p>
</sec>
<sec sec-type="funding-information" id="s8">
<title>Funding</title>
<p>The author(s) declare that financial support was received for the research and/or publication of this article. This work was supported by the scientific research start-up funds of Jishou University for the introduction of talent (2024&#x2013;12), the Natural Science Foundation of Hunan Province(2025JJ70608) and the scientific research projects of Jishou University (Jdzd22015, Jdy23081).</p>
</sec>
<sec sec-type="COI-statement" id="s9">
<title>Conflict of interest</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="ai-statement" id="s10">
<title>Generative AI statement</title>
<p>The author(s) declare that no Generative AI was used in the creation of this manuscript.</p>
</sec>
<sec sec-type="disclaimer" id="s11">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<sec id="s12">
<title>Abbreviations</title>
<p>ALL, anterior longitudinal ligament; CL, capsular ligament; FE, finite element; ISL, interspinous ligament; LF, ligamentum flavum; PCD, percutaneous cement discoplasty; PCIF, percutaneous cement interbody fusion; PLL, posterior longitudinal ligament; PVP, percutaneous vertebroplasty; ROM, range of motion; TL, intertransverse ligament; SSL, supraspinous ligament.</p>
</sec>
<ref-list>
<title>References</title>
<ref id="B1">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ambati</surname>
<given-names>D. V.</given-names>
</name>
<name>
<surname>Wright</surname>
<given-names>E. J.</given-names>
</name>
<name>
<surname>Lehman</surname>
<given-names>R. J.</given-names>
</name>
<name>
<surname>Kang</surname>
<given-names>D. G.</given-names>
</name>
<name>
<surname>Wagner</surname>
<given-names>S. C.</given-names>
</name>
<name>
<surname>Dmitriev</surname>
<given-names>A. E.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Bilateral pedicle screw fixation provides superior biomechanical stability in transforaminal lumbar interbody fusion: a finite element study</article-title>. <source>Spine J.</source> <volume>15</volume> (<issue>8</issue>), <fpage>1812</fpage>&#x2013;<lpage>1822</lpage>. <pub-id pub-id-type="doi">10.1016/j.spinee.2014.06.015</pub-id>
</citation>
</ref>
<ref id="B2">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Camino</surname>
<given-names>W. G.</given-names>
</name>
<name>
<surname>Kido</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Pereira</surname>
<given-names>D. M.</given-names>
</name>
<name>
<surname>Estefan</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Bendersky</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Bassani</surname>
<given-names>J.</given-names>
</name>
<etal/>
</person-group> (<year>2020</year>). <article-title>Percutaneous cement discoplasty for the treatment of advanced degenerative disc conditions: a case series analysis</article-title>. <source>Glob. Spine J.</source> <volume>10</volume> (<issue>6</issue>), <fpage>729</fpage>&#x2013;<lpage>734</lpage>. <pub-id pub-id-type="doi">10.1177/2192568219873885</pub-id>
</citation>
</ref>
<ref id="B3">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Camino-Willhuber</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Norotte</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Bronsard</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Kido</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Pereira-Duarte</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Estefan</surname>
<given-names>M.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Percutaneous cement discoplasty for degenerative low back pain with vacuum phenomenon: a multicentric study with a minimum of 2 years of Follow-Up</article-title>. <source>World Neurosurg.</source> <volume>155</volume>, <fpage>e210</fpage>&#x2013;<lpage>e217</lpage>. <pub-id pub-id-type="doi">10.1016/j.wneu.2021.08.042</pub-id>
</citation>
</ref>
<ref id="B4">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Chen</surname>
<given-names>C. S.</given-names>
</name>
<name>
<surname>Cheng</surname>
<given-names>C. K.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>C. L.</given-names>
</name>
<name>
<surname>Lo</surname>
<given-names>W. H.</given-names>
</name>
</person-group> (<year>2001</year>). <article-title>Stress analysis of the disc adjacent to interbody fusion in lumbar spine</article-title>. <source>Med. Eng. Phys.</source> <volume>23</volume> (<issue>7</issue>), <fpage>485</fpage>&#x2013;<lpage>493</lpage>. <pub-id pub-id-type="doi">10.1016/s1350-4533(01)00076-5</pub-id>
</citation>
</ref>
<ref id="B5">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Chen</surname>
<given-names>S. H.</given-names>
</name>
<name>
<surname>Lin</surname>
<given-names>S. C.</given-names>
</name>
<name>
<surname>Tsai</surname>
<given-names>W. C.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>C. W.</given-names>
</name>
<name>
<surname>Chao</surname>
<given-names>S. H.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>Biomechanical comparison of unilateral and bilateral pedicle screws fixation for transforaminal lumbar interbody fusion after decompressive surgery--a finite element analysis</article-title>. <source>BMC Musculoskelet. Disord.</source> <volume>13</volume>, <fpage>72</fpage>. <pub-id pub-id-type="doi">10.1186/1471-2474-13-72</pub-id>
</citation>
</ref>
<ref id="B6">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ellingson</surname>
<given-names>A. M.</given-names>
</name>
<name>
<surname>Shaw</surname>
<given-names>M. N.</given-names>
</name>
<name>
<surname>Giambini</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>An</surname>
<given-names>K.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Comparative role of disc degeneration and ligament failure on functional mechanics of the lumbar spine</article-title>. <source>Comput. Methods Biomechanics Biomed. Eng.</source> <volume>19</volume> (<issue>9</issue>), <fpage>1009</fpage>&#x2013;<lpage>1018</lpage>. <pub-id pub-id-type="doi">10.1080/10255842.2015.1088524</pub-id>
</citation>
</ref>
<ref id="B7">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Fan</surname>
<given-names>C. Y.</given-names>
</name>
<name>
<surname>Hsu</surname>
<given-names>C. C.</given-names>
</name>
<name>
<surname>Chao</surname>
<given-names>C. K.</given-names>
</name>
<name>
<surname>Lin</surname>
<given-names>S. C.</given-names>
</name>
<name>
<surname>Chao</surname>
<given-names>K. H.</given-names>
</name>
</person-group> (<year>2010</year>). <article-title>Biomechanical comparisons of different posterior instrumentation constructs after two-level ALIF: a finite element study</article-title>. <source>Med. Eng. Phys.</source> <volume>32</volume> (<issue>2</issue>), <fpage>203</fpage>&#x2013;<lpage>211</lpage>. <pub-id pub-id-type="doi">10.1016/j.medengphy.2009.12.002</pub-id>
</citation>
</ref>
<ref id="B8">
<citation citation-type="journal">
<collab>GBD 2015 Disease and Injury Incidence and Prevalence Collaborators</collab> (<year>2016</year>). <article-title>Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015</article-title>. <source>Lancet</source> <volume>388</volume> (<issue>10053</issue>), <fpage>1545</fpage>&#x2013;<lpage>1602</lpage>. <pub-id pub-id-type="doi">10.1016/s0140-6736(16)31678-6</pub-id>
</citation>
</ref>
<ref id="B9">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Ghandour</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Pazarlis</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Lewin</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Isaksson</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>F&#xf6;rsth</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Persson</surname>
<given-names>C.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>An ex-vivo model for the biomechanical assessment of cement discoplasty</article-title>. <source>Front. Bioeng. Biotechnol.</source> <volume>10</volume>, <fpage>939717</fpage>. <pub-id pub-id-type="doi">10.3389/fbioe.2022.939717</pub-id>
</citation>
</ref>
<ref id="B10">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Grewal</surname>
<given-names>S. S.</given-names>
</name>
<name>
<surname>Hirsch</surname>
<given-names>J. A.</given-names>
</name>
<name>
<surname>Cancelliere</surname>
<given-names>N. M.</given-names>
</name>
<name>
<surname>Ghozy</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Pereira</surname>
<given-names>V. M.</given-names>
</name>
<name>
<surname>Dmytriw</surname>
<given-names>A. A.</given-names>
</name>
</person-group> (<year>2024</year>). <article-title>Efficacy and safety of percutaneous cement discoplasty in the management of degenerative spinal diseases: a systematic review and meta-analysis</article-title>. <source>Neuroradiol. J.</source> <volume>37</volume> (<issue>4</issue>), <fpage>434</fpage>&#x2013;<lpage>440</lpage>. <pub-id pub-id-type="doi">10.1177/19714009231212368</pub-id>
</citation>
</ref>
<ref id="B11">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Guo</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Wang</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Song</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Yang</surname>
<given-names>W.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Yang</surname>
<given-names>W.</given-names>
</name>
<etal/>
</person-group> (<year>2025</year>). <article-title>Biomechanical evaluation of oblique lateral interbody fusion with various fixation methods for degenerative lumbar scoliosis: a finite element analysis considering different bone densities</article-title>. <source>Front. Bioeng. Biotechnol.</source> <volume>13</volume>, <fpage>1562268</fpage>. <pub-id pub-id-type="doi">10.3389/fbioe.2025.1562268</pub-id>
</citation>
</ref>
<ref id="B12">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Jia</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Qi</surname>
<given-names>X.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Biomechanical evaluation of percutaneous cement discoplasty by finite element analysis</article-title>. <source>BMC Musculoskelet. Disord.</source> <volume>23</volume>, <fpage>594</fpage>. <pub-id pub-id-type="doi">10.1186/s12891-022-05508-1</pub-id>
</citation>
</ref>
<ref id="B13">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Kimura</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Shikata</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Odate</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Soeda</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Yamamura</surname>
<given-names>S.</given-names>
</name>
</person-group> (<year>2012</year>). <article-title>Risk factors for cage retropulsion after posterior lumbar interbody fusion: analysis of 1070 cases</article-title>. <source>Spine</source> <volume>37</volume> (<issue>13</issue>), <fpage>1164</fpage>&#x2013;<lpage>1169</lpage>. <pub-id pub-id-type="doi">10.1097/brs.0b013e318257f12a</pub-id>
</citation>
</ref>
<ref id="B14">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Kiss</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Varga</surname>
<given-names>P. P.</given-names>
</name>
<name>
<surname>Szoverfi</surname>
<given-names>Z.</given-names>
</name>
<name>
<surname>Jakab</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Eltes</surname>
<given-names>P. E.</given-names>
</name>
<name>
<surname>Lazary</surname>
<given-names>A.</given-names>
</name>
</person-group> (<year>2019</year>). <article-title>Indirect foraminal decompression and improvement in the lumbar alignment after percutaneous cement discoplasty</article-title>. <source>Eur. Spine J.</source> <volume>28</volume> (<issue>6</issue>), <fpage>1441</fpage>&#x2013;<lpage>1447</lpage>. <pub-id pub-id-type="doi">10.1007/s00586-019-05966-7</pub-id>
</citation>
</ref>
<ref id="B15">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Lee</surname>
<given-names>D.</given-names>
</name>
<name>
<surname>Park</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Song</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Jeong</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Kim</surname>
<given-names>D.</given-names>
</name>
</person-group> (<year>2018</year>). <article-title>Risk factors for posterior cage migration after Lumbar interbody fusion surgery</article-title>. <source>Asian Spine J.</source> <volume>12</volume> (<issue>1</issue>), <fpage>59</fpage>&#x2013;<lpage>68</lpage>. <pub-id pub-id-type="doi">10.4184/asj.2018.12.1.59</pub-id>
</citation>
</ref>
<ref id="B16">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Li</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Shao</surname>
<given-names>P.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>G.</given-names>
</name>
<etal/>
</person-group> (<year>2022</year>). <article-title>Biomechanical evaluation of effects of percutaneous cement discoplasty and percutaneous cement interbody fusion on spinal stability</article-title>. <source>Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi</source> <volume>36</volume> (<issue>11</issue>), <fpage>1407</fpage>&#x2013;<lpage>1412</lpage>. <pub-id pub-id-type="doi">10.7507/1002-1892.202206052</pub-id>
</citation>
</ref>
<ref id="B17">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Li</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>B.</given-names>
</name>
<name>
<surname>Liu</surname>
<given-names>Y.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Xu</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Shao</surname>
<given-names>P.</given-names>
</name>
<etal/>
</person-group> (<year>2022</year>). <article-title>Biomechanical evaluation of spinal column after percutaneous cement discoplasty: a finite element analysis</article-title>. <source>Orthop. Surg.</source> <volume>14</volume> (<issue>8</issue>), <fpage>1853</fpage>&#x2013;<lpage>1863</lpage>. <pub-id pub-id-type="doi">10.1111/os.13314</pub-id>
</citation>
</ref>
<ref id="B18">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Mihailidis</surname>
<given-names>H. G.</given-names>
</name>
<name>
<surname>Manners</surname>
<given-names>S.</given-names>
</name>
<name>
<surname>Churilov</surname>
<given-names>L.</given-names>
</name>
<name>
<surname>Quan</surname>
<given-names>G.</given-names>
</name>
</person-group> (<year>2017</year>). <article-title>Is spinal surgery safe in octogenarians?</article-title> <source>ANZ J. Surg.</source> <volume>87</volume> (<issue>7-8</issue>), <fpage>605</fpage>&#x2013;<lpage>609</lpage>. <pub-id pub-id-type="doi">10.1111/ans.13885</pub-id>
</citation>
</ref>
<ref id="B19">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Panjabi</surname>
<given-names>M. M.</given-names>
</name>
<name>
<surname>Oxland</surname>
<given-names>T. R.</given-names>
</name>
<name>
<surname>Yamamoto</surname>
<given-names>I.</given-names>
</name>
<name>
<surname>Crisco</surname>
<given-names>J. J.</given-names>
</name>
</person-group> (<year>1994</year>). <article-title>Mechanical behavior of the human lumbar and Lumbosacral spine as shown by three-dimensional load-displacement curves</article-title>. <source>J. Bone Jt. Surg. Am.</source> <volume>76</volume> (<issue>3</issue>), <fpage>413</fpage>&#x2013;<lpage>424</lpage>. <pub-id pub-id-type="doi">10.2106/00004623-199403000-00012</pub-id>
</citation>
</ref>
<ref id="B20">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Park</surname>
<given-names>M. K.</given-names>
</name>
<name>
<surname>Kim</surname>
<given-names>K. T.</given-names>
</name>
<name>
<surname>Bang</surname>
<given-names>W. S.</given-names>
</name>
<name>
<surname>Cho</surname>
<given-names>D. C.</given-names>
</name>
<name>
<surname>Sung</surname>
<given-names>J. K.</given-names>
</name>
<name>
<surname>Lee</surname>
<given-names>Y. S.</given-names>
</name>
<etal/>
</person-group> (<year>2019</year>). <article-title>Risk factors for cage migration and cage retropulsion following transforaminal lumbar interbody fusion</article-title>. <source>Spine J.</source> <volume>19</volume> (<issue>3</issue>), <fpage>437</fpage>&#x2013;<lpage>447</lpage>. <pub-id pub-id-type="doi">10.1016/j.spinee.2018.08.007</pub-id>
</citation>
</ref>
<ref id="B21">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Techens</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Eltes</surname>
<given-names>P. E.</given-names>
</name>
<name>
<surname>Lazary</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Cristofolini</surname>
<given-names>L.</given-names>
</name>
</person-group> (<year>2022</year>). <article-title>Critical review of the state-of-the-art on lumbar percutaneous cement discoplasty</article-title>. <source>Front. Surg.</source> <volume>9</volume>, <fpage>902831</fpage>. <pub-id pub-id-type="doi">10.3389/fsurg.2022.902831</pub-id>
</citation>
</ref>
<ref id="B22">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Techens</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Palanca</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>&#xc9;ltes</surname>
<given-names>P. E.</given-names>
</name>
<name>
<surname>Laz&#xe1;ry</surname>
<given-names>&#xc1;.</given-names>
</name>
<name>
<surname>Cristofolini</surname>
<given-names>L.</given-names>
</name>
</person-group> (<year>2020</year>). <article-title>Testing the impact of discoplasty on the biomechanics of the intervertebral disc with simulated degeneration: an in vitro study</article-title>. <source>Med. Eng. Phys.</source> <volume>84</volume>, <fpage>51</fpage>&#x2013;<lpage>59</lpage>. <pub-id pub-id-type="doi">10.1016/j.medengphy.2020.07.024</pub-id>
</citation>
</ref>
<ref id="B23">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Tsai</surname>
<given-names>P. I.</given-names>
</name>
<name>
<surname>Hsu</surname>
<given-names>C. C.</given-names>
</name>
<name>
<surname>Chen</surname>
<given-names>S. Y.</given-names>
</name>
<name>
<surname>Wu</surname>
<given-names>T. H.</given-names>
</name>
<name>
<surname>Huang</surname>
<given-names>C. C.</given-names>
</name>
</person-group> (<year>2016</year>). <article-title>Biomechanical investigation into the structural design of porous additive manufactured cages using numerical and experimental approaches</article-title>. <source>Comput. Biol. Med.</source> <volume>76</volume>, <fpage>14</fpage>&#x2013;<lpage>23</lpage>. <pub-id pub-id-type="doi">10.1016/j.compbiomed.2016.06.016</pub-id>
</citation>
</ref>
<ref id="B24">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Tsuang</surname>
<given-names>Y. H.</given-names>
</name>
<name>
<surname>Chiang</surname>
<given-names>Y. F.</given-names>
</name>
<name>
<surname>Hung</surname>
<given-names>C. Y.</given-names>
</name>
<name>
<surname>Wei</surname>
<given-names>H. W.</given-names>
</name>
<name>
<surname>Huang</surname>
<given-names>C. H.</given-names>
</name>
<name>
<surname>Cheng</surname>
<given-names>C. K.</given-names>
</name>
</person-group> (<year>2009</year>). <article-title>Comparison of cage application modality in posterior lumbar interbody fusion with posterior instrumentation--a finite element study</article-title>. <source>Med. Eng. Phys.</source> <volume>31</volume> (<issue>5</issue>), <fpage>565</fpage>&#x2013;<lpage>570</lpage>. <pub-id pub-id-type="doi">10.1016/j.medengphy.2008.11.012</pub-id>
</citation>
</ref>
<ref id="B25">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Varga</surname>
<given-names>P. P.</given-names>
</name>
<name>
<surname>Jakab</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Bors</surname>
<given-names>I. B.</given-names>
</name>
<name>
<surname>Lazary</surname>
<given-names>A.</given-names>
</name>
<name>
<surname>Sz&#xf6;v&#xe9;rfi</surname>
<given-names>Z.</given-names>
</name>
</person-group> (<year>2015</year>). <article-title>Experiences with PMMA cement as a stand-alone intervertebral spacer: percutaneous cement discoplasty in the case of vacuum phenomenon within lumbar intervertebral discs</article-title>. <source>Orthopade</source> <volume>44</volume>, <fpage>S1</fpage>&#x2013;<lpage>S7</lpage>.</citation>
</ref>
<ref id="B26">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Willhuber</surname>
<given-names>G. O. C.</given-names>
</name>
<name>
<surname>Bendersky</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Vilte</surname>
<given-names>C.</given-names>
</name>
<name>
<surname>Kido</surname>
<given-names>G.</given-names>
</name>
<name>
<surname>Pereira Duarte</surname>
<given-names>M.</given-names>
</name>
<name>
<surname>Estefan</surname>
<given-names>M.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Accuracy of intraoperative neuromonitoring during percutaneous cement discoplasty</article-title>. <source>Rev. la Fac. Ciencias M&#xe9;dicas C&#xf3;rdoba</source> <volume>78</volume> (<issue>3</issue>), <fpage>257</fpage>&#x2013;<lpage>263</lpage>.</citation>
</ref>
<ref id="B27">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Xue</surname>
<given-names>Y. D.</given-names>
</name>
<name>
<surname>Zhang</surname>
<given-names>Z. C.</given-names>
</name>
<name>
<surname>Dai</surname>
<given-names>W. X.</given-names>
</name>
</person-group> (<year>2021</year>). <article-title>Investigation of preoperative traction followed by percutaneous kyphoplasty combined with percutaneous cement discoplasty for the treatment of severe thoracolumbar osteoporotic vertebral compression fractures</article-title>. <source>Int. J. Gen. Med.</source> <volume>14</volume>, <fpage>6563</fpage>&#x2013;<lpage>6571</lpage>. <pub-id pub-id-type="doi">10.2147/ijgm.s333532</pub-id>
</citation>
</ref>
<ref id="B28">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Yamada</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Nakamae</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Nakanishi</surname>
<given-names>K.</given-names>
</name>
<name>
<surname>Kamei</surname>
<given-names>N.</given-names>
</name>
<name>
<surname>Hiramatsu</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Okuda</surname>
<given-names>T.</given-names>
</name>
<etal/>
</person-group> (<year>2021</year>). <article-title>Long-term outcome of targeted therapy for low back pain in elderly degenerative lumbar scoliosis</article-title>. <source>Eur. Spine J.</source> <volume>30</volume> (<issue>7</issue>), <fpage>2020</fpage>&#x2013;<lpage>2032</lpage>. <pub-id pub-id-type="doi">10.1007/s00586-021-06805-4</pub-id>
</citation>
</ref>
<ref id="B29">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Yamamoto</surname>
<given-names>I.</given-names>
</name>
<name>
<surname>Panjabi</surname>
<given-names>M. M.</given-names>
</name>
<name>
<surname>Crisco</surname>
<given-names>T.</given-names>
</name>
<name>
<surname>Oxland</surname>
<given-names>T.</given-names>
</name>
</person-group> (<year>1989</year>). <article-title>Three-dimensional movements of the whole lumbar spine and lumbosacral joint</article-title>. <source>Spine</source> <volume>14</volume> (<issue>11</issue>), <fpage>1256</fpage>&#x2013;<lpage>1260</lpage>. <pub-id pub-id-type="doi">10.1097/00007632-198911000-00020</pub-id>
</citation>
</ref>
<ref id="B30">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zhang</surname>
<given-names>H.</given-names>
</name>
<name>
<surname>Gao</surname>
<given-names>J.</given-names>
</name>
<name>
<surname>Tang</surname>
<given-names>X.</given-names>
</name>
</person-group> (<year>2024</year>). <article-title>Percutaneous cement discoplasty for the treatment of lumbar degenerative diseases: a system review and meta-analysis</article-title>. <source>Medicine</source> <volume>103</volume> (<issue>34</issue>), <fpage>e39345</fpage>. <pub-id pub-id-type="doi">10.1097/md.0000000000039345</pub-id>
</citation>
</ref>
<ref id="B31">
<citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname>Zhong</surname>
<given-names>Z. C.</given-names>
</name>
<name>
<surname>Chen</surname>
<given-names>S. H.</given-names>
</name>
<name>
<surname>Hung</surname>
<given-names>C. H.</given-names>
</name>
</person-group> (<year>2009</year>). <article-title>Load- and displacement-controlled finite element analyses on fusion and non-fusion spinal implants</article-title>. <source>Proc. Inst. Mech. Eng. H.</source> <volume>223</volume> (<issue>2</issue>), <fpage>143</fpage>&#x2013;<lpage>157</lpage>. <pub-id pub-id-type="doi">10.1243/09544119jeim476</pub-id>
</citation>
</ref>
</ref-list>
</back>
</article>