Biomechanical evaluation of absorbable shape memory polyurethane lumbar interbody fusion cage

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.