基于多孔弹性模型的脊椎关节生物力学特性和体液流动特性研究

Biomechanical and fluid flowing characteristics of lumbar segment predicted by poroelastic model

建立了L4/L5段人体腰椎关节的非线性多孔弹性有限元模型,并对其施加1000N振动载荷1h,考察在不同的振动频率(1Hz、4Hz、8Hz、11.5Hz、15Hz)下腰椎关节的变形、应力分布和体液流动情况;并对不同频率作用下脊椎组织的生物力学特性进行了对比分析。结果表明,在不同频率振动载荷下,脊椎模型的应力分配、体液流量都呈现与振动载荷不同的周期性波动变化。振动载荷频率等于腰椎关节的固有频率11.5Hz时,椎间盘应力分配和体液流量波动的幅值最短;而振动频率为4Hz、8Hz、15Hz时各项指标波动的幅值比11.5Hz时小。振动过程中,椎间盘内外压力梯度的变化引起体液的流动,振动时间越长,总流失量越大。

To investigate the deformation of the intervertebral disc as well as the stress distribution and fluid flow situation under different frequencies(1Hz,4Hz,6Hz,8Hz,11.5Hz and 15Hz)of vibration loading,a nonlinear poroelastic finite element model of L4/L5 human intervertebral disc is developed first in this study,and the axial compression load is applied to the disc each for 1h to comparatively analyze the biomechanical characteristics under vibrational loads with different frequencies.The results show that,the stress distribution and the change of fluid flow of lumbar segment model show periodic variation and its period is different from the vibration period.When the frequency is equal to the natural frequency of lumbar joints at 11.5Hz,the amplitude of stress distribution and fluid flow of intervertebral disc is the largest,while the period of time variation of various indicators at 4Hz,8Hz and 15Hz is smallest.During vibration,changes in pressure gradient between the intervertebral disc cause fluid flow,the longer the vibration continues,the larger the total loss.