Li Jie, Du Zengfeng, Cao Shuai, Lu Teng, Sun Zhongwei, Wei Hongyu, Li Haopeng, Zhang Ting
Department of Orthopedics, Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Department of Orthopedics, The First Hospital of Yulin, Yulin, Shaanxi, China.
Front Bioeng Biotechnol. 2025 Jan 7;12:1510597. doi: 10.3389/fbioe.2024.1510597. eCollection 2024.
Currently, some novel rods with lower elastic modulus have the potential as alternatives to traditional titanium alloy rods in lumbar fusion. However, how the elastic modulus of the rod (rod-E) influences the biomechanical performance of lumbar interbody fusion remains unclear. This study aimed to explore the quantitative relationships between rod-E and the biomechanical performance of transforaminal lumbar interbody fusion (TLIF).
The intact finite element model of L1-S1 was constructed and validated. Then 12 TLIF models with rods of different elastic moduli (ranging from 1 GPa to 110 GPa with an interval of 10 GPa) were developed. The range of motion (ROM) of the fixed segment, mean strain of the bone graft, and maximum von Mises stresses on the cage, endplate, and posterior fixation system models were calculated. Finally, regression analysis was performed to establish functional relationships between rod-E and these indexes.
Increasing rod-E decreased ROM of the fixed segment, mean strain of the bone grafts, and peak stresses on the cage and endplate, while increasing peak stress on the screw-rod system. When rod-E increased from 1 GPa to 10 GPa, ROM decreased by 10.4%-39.4%. Further increasing rod-E from 10 GPa to 110 GPa resulted in a 9.3%-17.4% reduction in ROM. The peak stresses on the posterior fixation system showed a nonlinear increase as the rod-E increased from 1 GPa to 110 GPa under most loading conditions. The values for all fitting curves ranged from 0.76 to 1.00.
The functional relationships between rod-E and the biomechanical properties of TLIF were constructed comprehensively. When the rod-E exceeds 10 GPa, further increases may not significantly improve stability, however, it may increase the risk of fixation failure. Therefore, a rod with an elastic modulus of approximately 10 GPa may provide optimal biomechanical properties for TLIF.
目前，一些具有较低弹性模量的新型棒材有潜力成为腰椎融合术中传统钛合金棒材的替代品。然而，棒材的弹性模量（棒材-E）如何影响腰椎椎间融合的生物力学性能仍不清楚。本研究旨在探讨棒材-E与经椎间孔腰椎椎间融合术（TLIF）生物力学性能之间的定量关系。
构建并验证L1-S1完整有限元模型。然后建立12个具有不同弹性模量（范围为1 GPa至110 GPa，间隔为10 GPa）棒材的TLIF模型。计算固定节段的活动度（ROM）、植骨的平均应变以及椎间融合器、终板和后路固定系统模型上的最大von Mises应力。最后，进行回归分析以建立棒材-E与这些指标之间的函数关系。
增加棒材-E可降低固定节段的ROM以及植骨的平均应变，还有椎间融合器和终板上的峰值应力，同时增加螺杆系统上的峰值应力。当棒材-E从1 GPa增加到10 GPa时，ROM下降了10.4%-39.4%。将棒材-E从10 GPa进一步增加到110 GPa导致ROM降低了9.3%-17.4%。在大多数加载条件下，随着棒材-E从1 GPa增加到110 GPa，后路固定系统上的峰值应力呈非线性增加。所有拟合曲线的值范围为0.76至1.00。
全面构建了棒材-E与TLIF生物力学性能之间的函数关系。当棒材-E超过10 GPa时，进一步增加可能不会显著提高稳定性，然而，这可能会增加固定失败的风险。因此，弹性模量约为10 GPa的棒材可能为TLIF提供最佳生物力学性能。
