椎间盘高度降低及退变对腰椎生物力学影响的有限元分析

目的：分析椎间盘高度降低及退变对腰椎活动节段生物力学的影响。方法：首先采用一种新型CAD方法精确构建腰椎L4-5，活动节段正常高度椎间盘（NHD）、单纯高度降低椎间盘（PHDD）、椎间盘高度降低合并严重退变（DHDD）三种有限元模型。垂直压缩载荷下，分别对3种有限元模型的生物力学参数进行测试。结果：椎间盘高度降低及退变对腰椎活动节段轴向移位、后外侧椎间盘膨出、纤维环纤维应力最大值有明显的影响，DHDD模型的椎体一终板界面应力分布与NHD和PHDD模型明显不同。结论：高度降低后椎间盘刚度明显增加，DHDD最不易发生内层纤维环纤维破裂，关节突关节间隙与轴向移位比值是决定椎间盘承载力大小的关键因素，退变椎间盘对压缩应力有明显分散传递作用。

The effect of disc height and degeneration on the mechanical behavior of lumbar spine:A finite element analysis

Objective: To evaluate the effects of disc height and degeneration on mechanical behavior of human lumbar spine segments. Methods: A new effective CAD method was used to accurately establish three finite element models, including normal height disc (NHD) model, pure height decreased disc (PHDD) model and degeneration combined height decrease disc (DHDD) model. The biomechanical parameters of three finite element models were measured under axial compressive load. Results: The height and degeneration of disc had obviously effects on the mechanical behavior of lumbar spine segment in terms of axial displacement, posterolateral disc bulge, the maximum stress in the peripheral anulus fibers. The stress distribution differed between DHDD and non-DHDD model. Conclusions: The stiffness of disc obviously increases after height decreasing. The happening of disruption of inner anulus fibers is the lowest in DHDD model. The ratio between the gap of facet articulation and axial displacement are crucial to determine the load strength of disc. The degenerated disc plays an effective role for stress distribution.