腰骶部椎间融合支架的改进及力学性能研究

Improvement and biomechanical measurement of allograft cortical fusion cage for lumbosacral interbody fusion

目的比较新型自制胫骨皮质支架与钛合金融合器、髂骨块在生物力学实验中的各项结果,了解新型胫骨皮质支架的生物力学稳定性,为临床应用提供理论依据。方法将16具小牛脊柱标本随机均分为4组:正常(NS)组、钛合金椎间融合支架(Tis)组、胫骨皮质融合支架(TS)组、髂骨块融合(LB)组,其中Tis、TS、LB组分别加后路内固定(F)记为TisF、TSF、LBF组。分别测定各组的应变、位移、刚度、极限力学指标等数据,采用F检验、SNK检验等,通过SPSS19.0软件进行统计学分析。结果实验显示在250 N载荷时,不同处理组在中立位时应变值排序结果如下:(TSF=NS=Tis=TisF)<LBF<TS<LB。载荷为250 N时各组中立位的纵向位移值大小排序:NS<TisF<TSF<LBF。载荷为250 N时各组中立位的水平位移大小排序:NS<(TisF=TSF)<LBF。不同应力强度的大小排序为:LB<LBF<TS<(TSF=Tis)<TisF。轴向刚度的大小顺序为:(TSF=LBF)<TisF<NS。弯曲刚度的大小排序为:LBF<TSF<TisF。极限载荷的大小排序为:TisF>TSF>LBF。结论改进后的异体骨支架的生物力学性能优于髂骨块,差于钛合金融合器。建议在使用支架时加用后路椎弓根钉内固定,以增加固定的强度。考虑到钛合金的金属特性及不可降解性,皮质骨支架在使用中可能有一定的优越性。

Objective To evaluate the biomechanical stability of a new kidney-shaped interbody fusion cage. Meth- ods Total 16 fresh calf spine specimens were randomly divided into four groups： NS （normal group） , TIS （titani- um interbody fusion stent group）, TS （ tibial cortical bone fusion stent group ）, LB （ iliac bone fusion group ）, where Tis group,TS group, the LB group plus posterior fixation （F） was recorded as TisF, TSF, LBF group. The strain,migration,stress intensity, rigidity, the maximum biomechanics of the Tt2 -L5 segment were meaured on a Fluid-pressure univeral test machine in each group. The results of the experiments used the F test and SNK analysis by SPSS 19.0 software. Results The descending order of the strain of different grops was LB, TS, LBF, TSF, NS, Tis, TisF,while LBF, TSF, NS and TS were statistically equal. Then the descending order of the axial migration was LBF, TSF, TisF, NS. The descending order of the horizontal migration was LBF, TSF, TisF, NS, while TSF was equal to TisF statistically. Then the descending order of stress intensity was TisF,TSF, Tis,TS, LBF, LB, while TSF was e- qual to Tis. And the descending order of the axial rigidity was NS, TisF, LBF, TSF, while LBF was equal to TSF. The descending order of bending stiffness was TisF, TSF, LBF. At last, the descending order of limit load was TisF, TSF, LBF. Conclusion The biomechanical properties of the improved allogeneie bone scaffold is superior to the iliac bone, worse than the titanium fusion. It is proposed to use the cortical bone scaffold with posterior pedicle screw fix- ation, and can increase the stability of the fixation. Titanium interbody fusion cage has special characteristics as a kind of metal,and can not be degraded. However, cortical bone scaffold has some advantages in use.