皮质骨钉道螺钉固定治疗腰椎结核的有限元分析

Finite element analysis on the treatment of lumbar tuberculosis with cortical bone trajectory screw fixation

目的建立3种不同内固定系统植入人体内的三维模型,互相之间进行力学参数对比,分析皮质骨钉道(CBT)螺钉系统治疗腰椎结核的临床可行性。方法实验通过对广西壮族自治区人民医院于2020年6月30日招募的1名正常成年志愿者L2~L4腰椎的CT数据进行建模,在Ansys中对3种模型施加500 N压力,比较内固定系统、钛笼底部、末节椎体椎体的受力、位移、应力分布以及不同工况下椎体定点角度变化,从生物力学的角度解释CBT螺钉固定系统治疗腰椎结核的优势。结果结果显示,CBT螺钉固定系统在侧弯时最大应力为194.84 N,传统椎弓根螺钉固定最大应力为196.48 N,结果基本相同。后伸时,CBT螺钉固定系统在对抗后伸扭矩时最大应力为104.17 N,观察位移可以或得相同结果,这表明CBT螺钉固定系统可以获得更坚强的稳定性。相邻阶段的短椎弓根螺钉与CBT螺钉对比可以看出,CBT螺钉固定系统可以获得更满意的稳定性。结论与短椎弓根螺钉固定系统比较,CBT螺钉固定系统可以更有效重建腰椎结核术后的稳定性,同时保留了腰椎更多运动节段,在临床上应当推广使用。

Objective A three dimensional models of three different internal fixation systems implanted in human body were established,and the mechanical parameters were compared among each other to analyze the clinical feasibility of the cortical bone trajectory(CBT)screw system in the treatment of lumbar tuberculosis.Methods The experiments were performed by modeling CT data of L2-L4 lumbar vertebrae of one normal adult volunteer recruited by the People′s Hospital of Guangxi Zhuang Autonomous Region on June 30,2020.A pressure of 500 N was applied to the three models in Ansys to compare the force,displacement,stress distribution of the internal fixation system,the bottom of the titanium cage,and the end vertebral body vertebrae,as well as the change of the vertebral body fixation angle under different working conditions to explain the advantages of the CBT screw fixation system for the treatment of lumbar spinal tuberculosis from the viewpoint of biomechanics.Results The CBT screw fixation system has a maximum stress of 194.84 N in lateral bending and a maximum stress of 196.48 N in conventional pedicle screw fixation,with essentially the same results.In posterior extension,the CBT screw fixation system has a maximum stress of 104.17 N against posterior extension torque,and the same results can be obtained by observing the displacement,which indicates that the CBT screw fixation system can obtain stronger stability.The comparison between short pedicle screws and CBT screws in adjacent stages shows that the CBT screw fixation system can obtain a more satisfactory stability.Conclusion Compared with the short pedicle screw fixation system,the CBT screw fixation system is more effective in restoring stability after lumbar tuberculosis,while retaining more motion segments oflumbar spine.It should be widely used in clinical practice.