可吸收形状记忆聚氨酯腰椎间融合器的生物力学评价

Biomechanical evaluation of absorbable shape memory polyurethane lumbar interbody fusion cage

摘要:

目的：评价自主研制的可吸收形状记忆聚氨酯（shape memory polyurethane，SMPU）腰椎间融合器（cage）在尸体腰椎单节段的生物力学特性。方法：将15具腰骶椎（L1～S1）标本随机分为3组：自体髂骨组（n=5），SMPU cage组（n=5），聚醚醚酮（polyetheretherketone，PEEK）cage组（n=5）。通过腰椎侧方入路，摘除L3～4椎间盘髓核后植入3种内植物，在力学试验机上测试每组标本术前与术后的运动范围（range of motion，ROM）及轴向破坏载荷。结果：ROM结果显示：术前自体髂骨组、SMPU cage组及PEEK cage组在前屈、后伸、左侧弯、右侧弯、左旋转、右旋转6个方向上的ROM相比较，差异均无统计学意义（P＞0.05）。自体髂骨组在6个方向上的术后ROM均较术前明显增加（P<0.05）；SMPU cage组在6个方向上的术后ROM均较术前明显减少（P<0.05）；PEEK cage组在6个方向上的术后ROM均较术前明显减少（P<0.05）。SMPU cage组与PEEK cage组术后在6个方向上的ROM均明显低于自体髂骨组（P<0.05）；SMPU cage组与PEEK cage组术后在6个方向上的ROM相比较，差异无统计学意义（P＞0.05）。轴向压缩测试结果显示：PEEK cage组的破坏载荷较SMPU cage组和自体髂骨组明显增加（P=0.000），SMPU cage组的破坏载荷较自体髂骨组明显增加（P=0.000）。结论：SMPU cage能满足腰椎椎间融合的初始稳定性，并能够承载腰椎的生理负荷。

Abstract:

Objective：To evaluate the biomechanical properties of the self-designed absorbable lumbar interbody fusion cage in a sin－gle-level of cadaveric lumbar spine. Methods：Fifteen lumbosacral（L1-S1） specimens were randomly divided into three groups：auto－genous iliac bone group（n=5），shape memory polyurethane（SMPU） cage group（n=5），polyetheretherketone（PEEK） cage group（n=5）. Three different intervertebral implants were implanted by lateral lumbar interbody fusion after complete discectomy（L3-4） was per－formed. The axial failure load and ROM between preoperation and postoperation were tested by a mechanical testing machine. Results：The ROM showed that there was no observed statistical difference in the preoperative ROM of all directions among three groups（P>0.05）. In the autogenous iliac bone group，the ROM in all directions of postoperation was significantly higher than that of preoperation（P<0.05）. In the SMPU cage group，the ROM in all directions of postoperation was significantly lower than that of preop－eration（P<0.05）. In the PEEK cage group，the ROM in all directions of postoperation was significantly lower than that of preoperation（P<0.05）. The postoperative ROM of all directions was significantly lower in SMPU cage group and PEEK cage group than autoge－nous iliac bone group（P<0.05）. There was no observed statistical difference in the postoperative ROM of all directions between SMPU cage group and PEEK cage group（P＞0.05）. In axial compression testing，the failure load of PEEK cage group was significantly higher than that of SMPU cage group and autogenous iliac bone group（P=0.000），and the failure load of SMPU cage group was significantly higher than that of autogenous iliac bone group（P=0.000）. Conclusion：SMPU cage can meet initial stability and bear the lumbar physiological load for lumbar interbody fusion.