寰枢椎关节间融合器的拓扑优化设计

Topology optimization design of atlantoaxial interarticular cage

目的探讨结构拓扑优化技术在寰枢椎关节间融合器设计的应用效果。方法选择1名健康志愿者,进行寰枕交界部位CT扫描,建立寰枢椎三维几何模型;对寰枢椎内固定系统模型基于边界反演法进行材料参数反演,构建各向同性材料参数下的简化模型,采用变密度法对植骨窗部分进行拓扑优化设计,获得植骨窗体积最大且结构刚度满足要求的结构,并几何重构为新型寰枢椎侧块关节间融合器(Cage A)。模拟融合器植入,比较CageA与传统融合器(Cage B)植入后,椎体、融合器及植骨内部应力响应,对植入融合器和椎体力学响应进行评估。结果与传统融合器(Cage B)相比,Cage A模型最大应力明显降低,且应力较均匀分布在支撑面上;在后伸状态下,植入Cage B的整体模型形变峰值明显降低;Cage B植入的椎体最大应力值、植骨体积占比无明显变化。结论借助结构拓扑优化技术设计的寰枢椎关节间融合器,应力分布均匀,椎体受力小。该方法可以实现具有针对性的个体化融合器设计。

Objective To investigate the application value of topology optimization technology in the design of atlantoaxial interarticular cage.Methods Three dimensional model of atlantoaxial vertebrae was established by scanning CT in a healthy volunteer.Based on this simplified model,topology optimization design was carried out for the atlantoaxial interarticular cage device.A new atlantoaxial cage(Cage A)was designed through topology optimization.The internal stress responses of Cage A and the traditional cage to the vertebral body were compared,and the mechanical properties of the fusion apparatus were evaluated.Results Compared with the traditional cage,the maximum stress of Cage A model was significantly reduced,and the stress was evenly distributed on the support surface.In the posterior extension state,the deformation peak value of the overall model with Cage B was significantly reduced.There were no significant changes in the maximum stress value and the proportion of bone graft volume in the vertebrae implanted by Cage B.Conclusions Compared with the traditional cage,the atlantoaxial interarticular cage designed by topological optimization technology has a more uniform stress distribution and reduces the risk of fusion cage settlement.This method can realize individualized cage design.