腰椎终板结构的生物力学研究

Biomechanical research on structural properties of lumbar endplates

目的:研究腰椎终板不同位点的生物力学特性分布规律.方法:选用人体新鲜腰椎标本30椎,对终板上平面的24个测试点进行压缩加载试验,用直径1.5 mm的半球形压头以12 mm/min的速度垂直终板平面下压,有所得的力-压缩力位移曲线计算最大压缩力,采用析因分析对实验数据进行统计学处理.结果:①L1-L3与L4-L5上终板平面最大压缩力差异具有统计学意义(P<0.05),L1-L2与L3-L5下终板平面最大压缩力的差异具有统计学意义(P<0.05),腰椎终板平面最大压缩力由上到下有逐渐增大的趋势.②L1-L5腰椎上终板平面横线a与其余各线差异具有统计学意义(P<0.05).纵线1,6与其余各线差异具有统计学意义(P<0.05).下终板平面横线a与其余各线差异具有统计学意义(P<0.05).纵线3,4线与其余各线差异具有统计学意义(P<0.05).③L3-L5上、下终板的最大压缩力差异均有统计学意义(P<0.05),余椎体差异无统计学意义.结论:L1-L5终板平面最大压缩力由上到下有逐渐增大的趋势,腰椎终板平面的后外侧部是椎体生物力学强度最大的部位,外周部的最大抗压力大于中央部,L3-L5椎体下终板平面的最大抗压力大于上终板平面,在进行椎间手术时植入物应尽量放置于终板的后外侧部以减少术后沉陷率.

AIM： To determine the distribution of the biomechanical properties of the lumbar endplates. METHODS： Indentation tests which were perpendicular to the endplate surface were performed at 24 standardized test sites in bony endplates of intact human lumbar vertebra using a 1.5 mm diameter, hemispherical indenter with a rate of 12 mm/min. The failure load at each test site was determined using the load-dlsplacement curves. Data were analyzed statistically. RESULTS： （ 1 ） There was a significant difference in failure load of the superior endplates between L1 -L3 and L4-L5 （ P 〈 0.05 ）. The difference in failure load of the inferior endplates was also significant among L1-L2 and L3-L5 （P 〈 0.05）. The failure load of the lumbar endplates showed an increasing tendency from up to down. （2） There was a significant difference in failure load of the superior lumbar endplate between horizontal line a and the other lines （P 〈 0.05 ）. The difference between vertical line 1 or 6 and the other lines of the superior lumbar endplates had statistical significance （P 〈 0.05 ） ; There was also a significant difference in failure load of the inferior lumbar endplate between horizontal line a and the other lines （P 〈 0.05）. The difference between vertical line 3 or 4 and the other lines of the inferior lumbar endplates had statistical significance （P 〈 0.05 ）. （ 3 ） The strength of the lumbar inferior endplates was significantly higher than that of the lumbar superior endplates between L3-L5 （P 〈 0.05 ）. No difference was noted in the strength between the other lumbar vertebra. CONCLUSION： The failure load of the lumbar endplates has an increasing tendency from up to down. The peripheral and posterior test sites are stronger than the other sites. The strength of the lumbar endplates increases from the center of bone to the margin. The strength of the inferior endplates is significantly higher than that of the superior endplates between L3-L5. Implants should be placed in posterior-lateral regionof lumbar endplates so that subsidence syndrome can be reduced as possible.