一种新型腰椎可降解椎间融合器的体外生物力学评价

In vitro biomechanical evaluation of a model of biodegradable lumbar intervertebral fusion cage

目的介绍一种新型腰椎可降解椎间融合器(cage)的设计理念和结构,对其生物力学性能进行初步评价。方法采用新型可降解骨水泥-磷酸镁水泥(Magnesium phosphate cement,MPC)经过特殊模具压缩凝固成可降解椎间融合器作为实验组(n=8),大小型号相同聚醚醚酮(PEEK)椎间融合器(n=8)及取猪髂骨块做成的三面皮质骨椎间融合器(n=8)作为对照组,利用Instron 10000N生物力学机做压缩载荷测试。当各组椎间融合器受压丢失椎间融合器高度1/3时即判定为椎间融合器失效,记录椎间融合器的轴向压缩栽荷及其刚度。若未达到丢失高度1/3时即发生椎间融合器损毁的,记录损毁时的位移、轴向压缩栽荷及其刚度。结果 MPC cage组压缩损毁时丢失的高度明显小于PEEK cage组及髂骨块cage组,差异有显著统计学意义(<0.01);MPC cage组压缩损毁时所承受载荷明显高于PEEK cage组及髂骨块cage组丢失高度1/3时所承受载荷,差异存在显著统计学意义(<0.01);MPC cage自身刚度远远高于PEEK cage及髂骨块cage,差异存在显著统计学意义(<0.01)。结论磷酸镁可降解椎间融合器(MPC cage)具有优良的抗形变能力及能够承受较大的压力载荷,能够提供人体腰椎间隙的支撑-压缩稳定作用,能满足临床植入的生物力学要求。

Objective To introduce the design concept and structure of a new type of biodegradable lumbar intervertebral fusion cage and to evaluate its biomechanical properties. Methods A novel type of biodegradable bone cement- magnesium phosphate cement（MPC）,which wascompressed and solidified by a special model to make intervertebral fusion cageswere identified as the experimental group（n=8）. The same size polyetheretherketone（PEEK） intervertebral fusion cages（n=8）and the pig iliac bone block-made intervertebral fusion cages（n=8）were the control groups. Compression load test using 10000 N Instron biomechanical machine. When the lumbar intervertebral fusion cage was compressed and the height of the intervertebral fusion cage loss 1/3, it was judged as failure, the load and stiffness of the intervertebral fusion cage was recorded. If the cage was damaged when the height lossless than 1/3 of its height, the displacement, the load and the stiffness wererecorded. Results As the MPC cagedamaged, its height loss was obvious less than the PEEK cage group and the pig iliac bone cage group, the difference was statistically significant（p〈 0.01）; Once the MPC cage wasdamaged, the load was significantly larger than the PEEK cage group and the pig iliac bone cage group at 1/3 of heightloss, the difference was statistically significant（p〈 0.01）; MPC cage group＇s stiffness was statistically significant than the PEEKcageandhe pig iliac bone cage group（p〈 0.01）. Conclusion Magnesium phosphate cement biodegradable intervertebral fusion cage, which has excellent anti deformation ability and can bear large pressure load, can provide the support and stability of lumbar intervertebral space, MPC cage can meet the biomechanics requirements of clinical implant.