腰椎椎弓根螺钉内固定对相邻节段运动和椎间盘内压的影响  

The effects of lumbar pedicle screw fixation on segmental motion and intradiscal pressure of adjacent segments

作　　者：李建江[1] 赵合元[1] 王志彬[2] 白人骁[2] 

机构地区：[1]天津医院脊柱外科 [2]天津医院骨研所,天津300211

出　　处：《中国临床解剖学杂志》2007年第5期590-594,共5页Chinese Journal of Clinical Anatomy

摘　　要：目的：研究腰椎坚强内固定后相邻节段运动范围和椎间盘内压的变化，并分析二者在相邻节段退变加速发生机制中的作用。方法：取7具小牛腰段脊柱标本（T11-S2），以Tenor椎弓根螺钉系统作为固定器械，在10Nm纯力矩加载下进行生物力学测定，测定各活动节段的运动范围和椎间盘内压，比较完整对照组、L4/5单间隙固定组和L3-L5，双间隙固定组间上述指标的变化，并对运动学指标（ROM）和椎间盘内压（IDP）增量进行相关分析和比较。结果：施加内固定后，上方相邻节段在各方向上的位移都明显增加，且随着固定范围的增大而更为明显，下方相邻节段仅在旋转方向上出现了明显的位移增加。比较而言，不论单间隙固定组还是双间隙固定组，也不论在何种运动方向上，椎间盘内压的变化量都极其细微。节段运动的增加与椎间盘内压升高成正相关关系。ROM增加比大于IDP增加比。结论：坚强内固定后相邻节段椎间盘退变加速现象是其运动学改变和椎间盘内压升高等多因素综合作用的结果。相邻节段应力集中、活动代偿增大和稳定性丢失是坚强内固定所带来的最直接、最主要的导致退变加速的生物力学改变。椎间盘内的压力也可因内固定而继发升高，但可能只是一个次要方面。Objective： To study the changes of range of motion and intradiscal pressure in the adjacent segments after rigid lumbar fixation, and analyze the respective role of the two factors in the mechanism of accelerated degeneration of the adjacent segments. Methods： 7 calf lumbar spine specimens （T13-S2） were biomechanically tested under pure moment of 10Nm loading with Tenor pedicle screw system as the fixation device. Range of motion and intradiscal pressure were measured in all unfused segments and compared among the control group （intact spine）,the single-segment-fixed group （L4/5） and the double-segment-fixed group （L3-L5）,and the correlation analysis and comparison between the increments of kinematic index （ROM） and intradiscal pressure （IDP） were performed. Results： After instrumentation, the segmental motion of the upper adjacent segments increased obviously in all directions, and increased as the range of fixation increased. The segmental motion of the lower adjacent segment increased only in direction of axial rotation. Comparatively, the changes of intradiscal pressure were extremely small,neither in single-segment-fixed group nor in double-segment-fixed group, and in whatever directions. Positive correlation between the increase of segmental motion and intradiscal pressure was shown. The increment of ROM was higher than that of IDP. Conclusions： Accelerated disc degeneration of adjacent segment after rigid fixation is the result of the compromise of kinematic changes and increase of intradiscal pressure together with some other factors. The stress concentration and compensative motion increase as well as loss of stability of adjacent segments are the most direct and primary biomechanical changes due to rigid fixation which may lead to accelerated disc degeneration. The intradiscal pressure will also increase after instrumentation secondarily, but appears to be just a minor aspect.

关 键 词：腰椎 内固定 椎间盘内压 椎间盘退变 生物力学 

分 类 号：R318.01[医药卫生—生物医学工程]