PEEK棒椎弓根螺钉内固定系统的三维有限元分析

Finite element analysis on PEEK rods pedicle screw system

目的通过三维有限元方法,比较PEEK棒与钛棒两种固定系统的椎间应力、螺钉应力、相邻节段椎间盘的生物力学变化。方法建立L3~L5的正常腰椎模型,在Pro/E软件中建立两种椎弓根螺钉系统模型。将两者组合构建L4/5节段内固定系统模型,在同样的约束和载荷条件下,比较屈伸、侧屈、旋转三种运动状态下,植骨融合前后,两种内固定装置的生物力学特点。结果在植入PEEK棒和传统钛棒后,在植骨融合前后两种状态下,头侧L3~L4相邻节段的纤维环和髓核应力PEEK棒组均较钛棒组降低。在植骨融合前PEEK棒组的椎间应力要更接近于正常的生理应力,PEEK棒组内固定螺钉表面的应力在植骨融合前后均较小。结论 PEEK棒与传统钛棒相比具有能减少内固定系统载荷与增加椎间植骨应力刺激、降低骨螺钉界面应力、减轻相邻节段载荷。

Objective To analyze the biomechanical characteristics of PEEK rods and Titanium rods, by comparing the stresses on the inter-vertebrae of the fixation segments and adjacent segments and the surface ofpediele screws using finite element analysis. Method Based on the established finite element model of L3-L~, the biomechanical characteristics of the both systems were compared at flexion-extension, lateral bending and axial rotation before and after interbody fusion with the same constraint and conditions. Results Higher stesses were observed on the inter-vertebrae of the fixation seg- ments and lower stresses were recorded on the inter-vertebrae of the adjacent segments for PEEK rods system under flex- ion-extension, lateral bending and axial rotation. Lower stresses on the pedicle screw were also found for PEEK rods. Conclusion In contrast to the Titanium rods, PEEK rods can support the fusion process by increasing loads on the anterior column bone graft while reducing loads on the bone screw interface, and may also reduce the stesses on the adjacent seg- ments.