Objective To study the bone stress change after implanting two different interbody fusion cages at L4-5 intervertebral body, and to provide the parameters for clinical use and cage design. Methods The specimens were obtained from healthy 8-month-old adult male calves. We used them to simulate disc herniation anteriorly at L4-5 intervertebral space. These specimens were randomly divided into two groups: a wedge-shaped fusion group and a cylindrical fusion group. The resistance strains were bonded to the relevant parts of the specimens, and then wires were welded and locations were marked. Subsequently, bending momen?tum (200N-CM) was applied and the strain value was measured at each moment. Finally, the data were analysed by SPSS 19 software, and the difference between the two groups were compared using paired t test. Results The maximum strain is was located at L5 anterior margin (A measurement), which was mainly due to slotting at the L4-5 vertebra clearance for interbody fusion cage implantation, and closing to the implanting site. The mini?mum strain was located at the L4 vertebral articular process (F measurement), which was due to being far away from the implanting site. The values of left bending of F measurement were 217.25±13.87 με×10-6 (wedge bone group) and 286.25 ± 4.86 με× 10-6 (cylindrical bone group) respectively, and the values of lateral bending are were-253.75 ± 6.08 με× 10-6 (wedge bone group) and-305.75 ± 8.02 με× 10-6 (cylindrical bone). Conclusion A larger stress change occurred at L5 anterior margin under the lateral bending stress after implantation of inter?vertebral fusion device. The stress change of wedge-shaped fusion group is less than that of the cylindrical fu?sion group.%目的:研究两种不同椎间融合器前路置入L4~L5椎间后测出周围骨质的应力改变,为临床及融合器设计提供相应参数.方法:新鲜脊柱标本来自于健康的8个月大小的成年雄性小牛,应用标准手法,模拟制作L4~L5椎间盘突出.两种椎间融合器分别为同种异体骨楔形融合器和同种异体骨圆柱形融合器,置入L4~L5椎间隙.在各组标本的相关部位黏贴电阻片之后焊上导线,标记位点,对标本依次施加200N-CM弯矩,测出各测点的应变值.采用SPSS 19.0软件完成统计处理,配对t检验对两组数据进行比较.结果:最大应变为L5椎体前上缘A测点,认为主要是由于对L4~L5椎间隙进行开槽,并进行椎间融合器置入;并且该部位还靠近植骨区,因此造成该部位的应力改变比较集中.最小应变点发生在L4椎体下关节突为F测点.F测点左侧弯实验应变值t检验结果:置楔形骨组(217.25±13.87)με×10-6,置圆柱形骨(286.25±4.86)με×10-6.F测点右侧弯实验应变值t检验结果:置楔形骨组(-253.75±6.08)με×10-6,置圆柱形骨(-305.75±8.02)με×10-6.与该测点距离植骨区较远有关.结论:在置入椎间融合器后,L5椎体前上缘在侧方弯应力作用下会引起较大的应力改变.楔形异体骨椎间融合各测点的应力改变要小于圆柱形椎间融合器.
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