振动载荷下不同入路腰椎椎间融合术的生物力学研究

Biomechanical study of different approach for lumbar interbody fusion surgeries under vibration load

振动导致的人体脊椎损伤以及多种腰椎疾病已引起国内外的广泛关注。为了探究振动载荷下不同入路腰椎椎间融合术联合一种棘突间内固定器—椎间辅助运动装置(DIAM)时的生物力学特性,以正常人体全腰椎三维有限元模型为基础,通过模拟临床术式,分别建立前路腰椎椎间融合术(ALIF)、经椎间孔腰椎椎间融合术(TLIF)和经侧方腰椎椎间融合术(LLIF)的有限元模型,融合节段为L4–L5,并将DIAM植入于L4–L5棘突间。通过瞬时动态分析,对ALIF、TLIF、LLIF模型在轴向循环载荷作用下的应力响应进行计算比较。结果表明,相比于ALIF和TLIF模型,LLIF模型中终板与椎间融合器间的接触力较高,其终板及DIAM上的冯·米塞斯应力较低,说明振动环境下LLIF的生物力学性能更好;当椎体间达到骨性融合后,三种手术模型的终板应力及DIAM应力均有所降低。综上所述,期望本文研究结果可为融合手术方案的选择以及术后腰椎振动保护方法的制定提供参考。

The human spine injury and various lumbar spine diseases caused by vibration have attracted extensive attention at home and abroad. To explore the biomechanical characteristics of different approaches for lumbar interbody fusion surgery combined with an interspinous internal fixator, device for intervertebral assisted motion(DIAM), finite element models of anterior lumbar interbody fusion(ALIF), transforaminal lumbar interbody fusion(TLIF) and lateral lumbar interbody fusion(LLIF) are created by simulating clinical operation based on a three-dimensional finite element model of normal human whole lumbar spine. The fusion level is at L4–L5, and the DIAM is implanted between spinous process of L4 and L5. Transient dynamic analysis is conducted on the ALIF, TLIF and LLIF models, respectively, to compute and compare their stress responses to an axial cyclic load. The results show that compared with those in ALIF and TILF models, contact forces between endplate and cage are higher in LLIF model, where the von-Mises stress in endplate and DIAM is lower. This implies that the LLIF have a better biomechanical performance under vibration. After bony fusion between vertebrae, the endplate and DIAM stresses for all the three surgical models are decreased. It is expected that this study can provide references for selection of surgical approaches in the fusion surgery and vibration protection for the postsurgical lumbar spine.