基于有限元分析的钛合金椎弓根螺钉抗弯性能结构优化

Optimization of pedicle screw thread structure based on finite element analysis

钛合金因其优异的力学性能和生物相容性,广泛用于椎弓根螺钉的制备。椎弓根螺钉植入人体后,受脊柱的屈曲伸展和横向弯曲作用,螺钉发生疲劳弯曲最终导致螺钉松动甚至断裂,影响植入稳定性。因此有必要对钛合金椎弓根螺钉抗弯性能进行研究。通过单因素实验与正交实验分析设计不同结构参数椎弓根螺钉,结合有限元分析与力学实验的方法,使用三点弯曲试验对钛合金椎弓根螺钉的抗弯性能进行模拟仿真与实验验证,并对螺钉结构参数进行优化。结果表明,模拟结果与实验结果吻合较好,螺钉结构参数对抗弯性能的影响顺序为外径大于螺纹深度大于螺距,最佳参数为螺钉外径5.5 mm、螺纹深度0.65 mm、螺距1.60 mm,优化后的螺钉对比标准椎弓根螺钉,最大支反力提高74.7%。

Titanium alloy is widely used to make pedicle screws because of its excellent mechanical and biocompatibility properties.After implantation,the screw is subjected to flexion and extension and lateral bending of the spine,which eventually leads to the loosening or even breaking of the screw and affects the stability of the implantation.Therefore,it is necessary to investigate the bending resistance of titanium alloy pedicle screws.The pedicle screws with different structural parameters were designed through single factor and orthogonal experimental analysis.Combined with finite element analysis and mechanical experiments,the three-point bending test was used to simulate and verify the bending resistance of titanium alloy pedicle screws,and the screw structural parameters were optimized.The results showed that the simulation results were consistent with the experimental results,and the influence of the screw structure parameters on the bending performance of the pedicle screw was in the order of outer diameter>thread depth>pitch.The optimal parameters were the screw outer diameter of 5.5 mm,thread depth of 0.65 mm,and pitch of 1.60 mm,which increased the maximum support reaction force by 74.7%compared to the standard pedicle screw.