3D打印个体化定制枕颈融合系统的三维有限元分析

Three-dimensional finite element analysis study of 3D printing occipitocervical fusion system

目的:运用三维有限元分析法对3D打印个体化定制枕颈融合系统(3D printing occipitocervical fusion system,3D-OCF)进行生物力学评价。方法:设计并研制3D-OCF,将该内固定系统与传统Summit内固定系统作对比,建立两套枕颈融合内固定方式的三维有限元模型,模拟术后上颈椎活动,分别在屈伸、侧屈及旋转6种工况下施加40 N垂直载荷及1.5 N·m力矩的预载荷,观察两种内固定系统固定下椎体活动度、枕骨位移峰值及内固定装置的应力分布。结果:在屈伸、侧屈、旋转6种工况下,与传统Summit内固定系统相比,3D-OCF固定的上颈椎各节段活动度明显降低,各节段整体活动度下降73.02%~100.00%;椎体位移峰值,与传统Summit内固定系统相比,3D-OCF固定的颈椎最大位移值明显降低,各个工况下下降了78.09%~95.73%;内固定系统应力分析,在屈伸、侧屈、旋转6种工况下,两套内固定系统所受最大应力值均在前屈状态下,3D-OCF最大应力值为37.43 MPa,Summit内固定系统最大应力值为533.32 MPa。3D-OCF的最大应力值与使用传统Summit内固定系统相比,3D-OCF各个工况的最大应力值明显降低,且各个工况下应力差均衡,无明显应力集中点。结论:3D-OCF能为枕颈融合内固定术能提供足够的强度和稳定性,且3D-OCF装置应力相对较为分散,系统装置发生断裂、失效的可能性小。

Objective:To evaluate the biomechanics of 3D printing occipital cervical fusion system(3D-OCF)using three-dimensional finite element analysis.Methods:A 3D-OCF was designed and developed,and compared with the traditional Summit internal fixation system.Two sets of three-dimensional finite element models of occipitocervical fusion internal fixation were established to simulate the postoperative movement of the upper cervical spine.A 40 N vertical load and a preload of 5 N·m torque were applied under flexion and extension,lateral flexion and rotation,respectively,to observe the vertebral activity,peak occipital displacement,and stress distribution of the internal fixation device under the fixation of the two internal fixation systems.Results:Under the six working conditions of flexion,extension,lateral flexion,and rotation,compared with the traditional Summit internal fixation system,the range of motion of each segment of the upper cervical spine fixed with 3D-OCF significantly decreased,and the overall range of motion of each segment decreased by 73.02%to 100.00%.Compared with the traditional Summit internal fixation system,the maximum displacement of the cervical spine after 3D-OCF fixation was significantly reduced,with a decrease of 78.09%to 95.73%under various working conditions.Stress analysis of the internal fixation system showed that the maximum stress values of the two sets of internal fixation systems under six working conditions of flexion,extension,lateral flexion,and rotation were both in the forward flexion state.The maximum stress value of 3D-OCF was 37.43 MPa,and the maximum stress value of Summit internal fixation system was 533.32 MPa.Compared with the traditional Summit internal fixation system,the maximum stress value of 3D-OCF under various working conditions was significantly reduced,and the stress difference under various working conditions was balanced,without significant stress concentration points.Conclusions:3D-OCF can provide sufficient strength and stability for occipitocervical fusion and internal fixation,and the stress of 3D-OCF device is relatively dispersed,with a small possibility of fracture and failure of the system device.