Biomechanical Evaluation Of Absorbable Shape Memory Polyurethane Lumbar Interbody Fusion Cage

Objective:To evaluate the biomechanical properties of the self-designed absorbable lumbar interbody fusion cage in a single-level of cadaveric lumbar spine.Methods:Fifteen lumbosacral(L1?S1)specimens were randomly divided into three groups: autogenous 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 performed.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 the preoperation(P<0.05);In the SMPU cage group,the ROM in all directions of postoperation was significantly lower than the preoperation(P<0.05);In the PEEK cage group,the ROM in all directions of postoperation was significantly lower than the preoperation(P<0.05).The postoperative ROM of all directions was significantly lower in SMPU cage group and PEEK cage group than autogenous 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 SMPU cage group and autogenous iliac bone group(P=0.000),and the failure load of SMPU cage group was significantly higher than autogenous iliac bone group(P=0.000).Conclusion: shape memory polyurethane cage can meet initial stability and bear the lumbar physiological load for lumbar interbody fusion.