一种新型设计的个性化椎间融合器及其生物力学分析

A newly designed personalized interbody fusion cage and its biomechanical analysis

椎间融合器在临床上经常用于脊柱感染性和退行性疾病的治疗,然而,进一步的临床应用通常受到一些缺陷的困扰,如应力遮挡和融合器沉降.本研究旨在提出一种新的脊柱融合器个性化设计理念:从微观到宏观的多尺度联合设计方法,创建与腰椎骨终板弹性模量和手术形式皆匹配的脊柱融合器.具体而言,引入三周期极小曲面来模拟聚醚醚酮(PEEK)融合器的多孔结构,通过调整孔隙参数以实现定制的宏观力学性能和孔隙结构的渗透性能。接着,针对经皮内镜下腰椎后路椎间融合术(PE-PLIF)进行多目标(屈伸、弯曲和扭转)拓扑优化,得到二次设计的新型多孔拓扑融合器。最后,将临床常用的钛融合器、PEEK融合器和本文设计的新型融合器进行基于有限元方法的生物力学对比分析。结果表明,与其他两种融合器相比,新型多孔拓扑融合器有着较低的骨-融合器界面应力和较高的内部移植骨应力和应变能密度,证明其有着较低的融合器沉降率和应力屏蔽的风险.总之,新型多孔拓扑融合器由于其良好的生物力学性能成为椎间融合术的理想选择.本文所提出的融合器设计思路和理念也可用于指导其他不同椎间融合术.

Interbody fusion cages are frequently used clinically for the treatment of infectious and degenerative diseases of the spine,however,further clinical applications are often plagued by some drawbacks,such as stress shielding and cage subsidence.This study aims to propose a new concept of personalized design of spinal cages:a multi-scale joint design approach from microscopic to macroscopic to create a spinal cage that matches the elastic modulus of the lumbar bony endplate and the surgical procedure.Specifically,a triple periodic minimal surface(TPMS)is introduced to simulate the porous structure of polyetheretherketone(PEEK)material cage,and the pore parameters are adjusted to achieve customized macroscopic mechanical properties and permeability of the pore structure.Then,multi-objective(flexion-extension,lateral bending,and axial torsion)topology optimization was performed for percutaneous endoscopic posterior lumbar interbody fusion(PE-PLIF)surgery to obtain a new porous topology cage of secondary design.Finally,a comparative biomechanical analysis based on the finite element method was performed on the commonly used clinical titanium cage,PEEK cage,and the new porous topology cage designed in this paper.The results showed that the new porous topology cage had lower bone-cage interface stress and higher internal bone graft stress and strain energy density(SED)compared to the other two cages,demonstrating a lower cage subsidence rate and risk of stress shielding.In conclusion,the new porous topology cage is an ideal choice for interbody fusion due to its good biomechanical properties.The cage design ideas and concepts presented in this paper can also be used to guide other different intervertebral fusion procedures.