Li Chao, Zhao Yao, Qi Longtao, Xu Beiyu, Yue Lei, Zhu Ranlyu, Li Chunde
Department of Orthopedics, Peking University First Hospital, Beijing, China.
Front Bioeng Biotechnol. 2024 Jul 11;12:1416046. doi: 10.3389/fbioe.2024.1416046. eCollection 2024.
Polyetheretherketone (PEEK) lumbar fusion rods have been successfully used in short-segment posterior instrumentation to prevent adjacent segment degeneration. However, limited studies have reported their application in lumbar long-segment instrumentation. This study aimed to compare the biomechanical performances of PEEK rods and titanium rods in lumbar long-segment instrumentation using finite element (FE) models, with the expectation of providing clinical guidance.
A lumbar FE model (A) and four lumbar fixation FE models (BI, CI, BII, CII) of the L1-S1 vertebral body were developed using CT image segmentation (A: intact model; BI: intact model with L2-S1 PEEK rod internal fixation; CI: intact model with L2-S1 titanium rod internal fixation; BII: intact model with L3-S1 PEEK rod internal fixation; CII: intact model with L3-S1 titanium rod internal fixation). A 150-N preload was applied to the top surface of L1, similar to the intact model. The stresses on the lumbar intervertebral disc, facet joint, pedicle screws, and rods were calculated to evaluate the biomechanical effect of the different fixation procedures in lumbar long-segment instrumented surgery.
Under the four physiological motion states, the average stresses on the adjacent segment intervertebral disc and facet joint in all fixation models were greater than those in the intact model. Furthermore, the average stresses on the adjacent segment intervertebral disc and facet joint were greater in models CI and CII than in models BI and BII, respectively. The average stresses on the pedicle screws and rods were decreased in models BI and BII compared with models CI and CII under the four physiological motion states, respectively.
The PEEK rod internal fixation system may have better biomechanical properties than the titanium rod internal fixation system in delaying adjacent segment degeneration, improving the lumbar function of postoperative patients, and reducing the risk of screw loosening and breakage in lumbar long-segment instrumentation.
聚醚醚酮（PEEK）腰椎融合棒已成功应用于短节段后路内固定，以预防相邻节段退变。然而，关于其在腰椎长节段内固定中的应用研究较少。本研究旨在使用有限元（FE）模型比较PEEK棒和钛棒在腰椎长节段内固定中的生物力学性能，以期为临床提供指导。
利用CT图像分割技术建立了L1-S1椎体的腰椎有限元模型（A）和四个腰椎固定有限元模型（BI、CI、BII、CII）（A：完整模型；BI：L2-S1 PEEK棒内固定的完整模型；CI：L2-S1钛棒内固定的完整模型；BII：L3-S1 PEEK棒内固定的完整模型；CII：L3-S1钛棒内固定的完整模型）。与完整模型类似，在L1的上表面施加150 N的预载荷。计算腰椎椎间盘、小关节、椎弓根螺钉和棒上的应力，以评估不同固定方法在腰椎长节段内固定手术中的生物力学效果。
在四种生理运动状态下，所有固定模型中相邻节段椎间盘和小关节上的平均应力均大于完整模型。此外，CI和CII模型中相邻节段椎间盘和小关节上的平均应力分别大于BI和BII模型。在四种生理运动状态下，BI和BII模型中椎弓根螺钉和棒上的平均应力分别低于CI和CII模型。
在腰椎长节段内固定中，PEEK棒内固定系统在延缓相邻节段退变、改善术后患者腰椎功能以及降低螺钉松动和断裂风险方面可能具有比钛棒内固定系统更好的生物力学性能。
