Nikkhoo Mohammad, Lu Meng-Ling, Chen Wen-Chien, Fu Chen-Ju, Niu Chi-Chien, Lin Yang-Hua, Cheng Chih-Hsiu
Department of Biomedical Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran.
Bone and Joint Research Center, Chang Gung Memorial Hospital, Linkou, Taiwan.
Front Bioeng Biotechnol. 2021 Apr 1;9:646079. doi: 10.3389/fbioe.2021.646079. eCollection 2021.
While spinal fusion using rigid rods remains the gold standard treatment modality for various lumbar degenerative conditions, its adverse effects, including accelerated adjacent segment disease (ASD), are well known. In order to better understand the performance of semirigid constructs using polyetheretherketone (PEEK) in fixation surgeries, the objective of this study was to analyze the biomechanical performance of PEEK versus Ti rods using a geometrically patient-specific poroelastic finite element (FE) analyses. Ten subject-specific preoperative models were developed, and the validity of the models was evaluated with previous studies. Furthermore, FE models of those lumbar spines were regenerated based on postoperation images for posterolateral fixation at the L4-L5 level. Biomechanical responses for instrumented and adjacent intervertebral discs (IVDs) were analyzed and compared subjected to static and cyclic loading. The preoperative model results were well comparable with previous FE studies. The PEEK construct demonstrated a slightly increased range of motion (ROM) at the instrumented level, but decreased ROM at adjacent levels, as compared with the Ti. However, no significant changes were detected during axial rotation. During cyclic loading, disc height loss, fluid loss, axial stress, and collagen fiber strain in the adjacent IVDs were higher for the Ti construct when compared with the intact and PEEK models. Increased ROM, experienced stress in AF, and fiber strain at adjacent levels were observed for the Ti rod group compared with the intact and PEEK rod group, which can indicate the risk of ASD for rigid fixation. Similar to the aforementioned pattern, disc height loss and fluid loss were significantly higher at adjacent levels in the Ti rod group after cycling loading which alter the fluid-solid interaction of the adjacent IVDs. This phenomenon debilitates the damping quality, which results in disc disability in absorbing stress. Such finding may suggest the advantage of using a semirigid fixation system to decrease the chance of ASD.
虽然使用刚性棒进行脊柱融合仍然是各种腰椎退行性疾病的金标准治疗方式，但其不良反应，包括加速的相邻节段疾病（ASD），是众所周知的。为了更好地了解在固定手术中使用聚醚醚酮（PEEK）的半刚性结构的性能，本研究的目的是通过几何形状特定于患者的多孔弹性有限元（FE）分析来分析PEEK与钛棒的生物力学性能。开发了十个特定于患者的术前模型，并通过先前的研究评估了模型的有效性。此外，根据术后图像对那些腰椎进行FE模型重建，用于L4-L5水平的后外侧固定。对植入器械的椎间盘和相邻椎间盘（IVD）在静态和循环加载下的生物力学反应进行了分析和比较。术前模型结果与先前的FE研究具有良好的可比性。与钛棒相比，PEEK结构在植入器械的节段显示出略微增加的活动范围（ROM），但在相邻节段的ROM降低。然而，在轴向旋转过程中未检测到显著变化。在循环加载期间，与完整模型和PEEK模型相比，钛结构的相邻IVD中的椎间盘高度损失、液体损失、轴向应力和胶原纤维应变更高。与完整模型和PEEK棒组相比，钛棒组在相邻节段观察到ROM增加、纤维环（AF）中的应力增加和纤维应变增加，这可能表明刚性固定存在ASD风险。与上述模式类似，循环加载后钛棒组相邻节段的椎间盘高度损失和液体损失显著更高，这改变了相邻IVD的流固相互作用。这种现象削弱了阻尼质量，导致椎间盘在吸收应力方面的功能障碍。这一发现可能表明使用半刚性固定系统可降低ASD发生几率的优势。
