新型后路腰椎椎间融合器的研制和动物实验研究

目的研制一种新型镍钛形状记忆合金腰椎椎体间融合器,通过动物实验了解其生物力学和组织学性能。方法本研究分为三个步骤。第一步将12个绵羊腰椎功能单位随机分成四组,每组3个,分别为对照组、髂骨植骨组(IG组)、interfix-lumbarcage组(cage组)和镍钛融合器组(NT组),进行生物力学测试,并检测镍钛融合器的力学性能;第二步将15只成年绵羊随机分为对照组、Interfix-lum-barcage组(cage组)和镍钛融合器组(NT组),每组5只,术后定期摄X线片了解椎间隙高度变化及融合进程;第三步将上述动物在术后6个月处死进行组织学观察以了解融合情况。所有数据采用统计学分析软件处理。结果对照组和髂骨植骨组与cage组和NT组在腰椎强度和轴向刚度方面相比,差异均有统计学意义(P<0.05)。镍钛融合器的最大破坏载荷可达11200N,安全系数达到1.2以上。cage组和NT组手术6个月时手术节段高度分别丧失16%和16.5%,但仍高于正常椎间隙高度(P<0.05)。光镜下可见新生骨小梁与宿主骨小梁发生连接。结论镍钛融合器的力学性能良好,可以作为腰椎椎间融合装置应用于临床。

The design and animal study of a new posterior lumbar interbody fusion cage

Objective To design a new type of posterior lumbar interbody fusion cage made of NiTi shape-memory alloy and to evaluate its histological and biomechanical behavior through animal study. Methods This study contained three steps of experiments which was posterior lumbar interbody fusion using different fusion materials and devices. At the first step, 12 sheep lumbar functional spinal units were randomly divided into 4 groups with 3 specimens in each group. There was one group with autogenous iliac crest bone dowel(IG), one group with interfix lumbar cage(cage), one group with NiTi-TFC(NT) and one group served as control group. Nondestructive biomechanical tests were carried out for each group. At the second step, 15 sheep were randomly divided into three groups with 5 specimens in each group. There was one group with cage and autogenous iliac crest graft, one group with NT and iliac crest and one group served as control group. All the animals were undergone imaging study regularly to evaluate the change of the intervertebral space heights and the process of fusion. At the third step, all animal from the second step were sacrificed 6 months later for histological analysis of the operated segments. All the data were statistically analyzed using SPSS 7.0. Results The strength and axial stiffness of the autogenous iliac crest bone dowel graft group and the control group were significantly different from the NT and cage group(P<0.05). The maximal destructive load of the NiTi-TFC was 11 200 N and the safety coefficient was above 1.2. The postoperative lose of intervertebral space height in cage and NT group was 16% and 16.5%, respectively but they were above normal intervertebral space height. Histological analysis showed new bone formation between interbody fusion device and vertebra body. Conclusion The biomechanical and histological behaviors of the NiTi-TFC were good. NiTi-TFC can be used as a reliable lumbar interbody fusion device.