经椎弓根皮质骨通道固定技术应用于胸腰段爆裂性骨折的有限元研究

The finite element analysis of the technology of cortical bone trajectory on the application of burst fracture in thoracolumbar spine

目的 :通过有限元分析方法将经椎弓根皮质骨通道(cortical bone trajectory,CBT)置钉技术应用于胸腰段爆裂性骨折,进行生物力学模拟分析,验证CBT技术应用的可行性。方法:模拟1例成年男性:(A)脊柱完整状态;(B)爆裂性骨折;(C)骨折化之后的4种固定组合:(1)4椎弓根钉2棒(P4组);(2)4 CBT 2棒(C4组);(3)6椎弓根钉2棒(P6组);(4)6CBT 2棒(C6组)。比较上述组别椎体模型节点的总变形及相应内固定模型节点的等效应力。结果 :4组内固定均能使骨折模型获得明显即刻稳定性。P4组各状态时总变形及内固定承受的等效应力普遍较其他模型增大;P6组模型各状态下的模型总位移及内固定所受等效应力较其他模型有明显优势;C6组较C4组各状态下的模型总变形及内固定承受的等效应力均有减少。结论:C4法和C6法固定与P6法相比仍有一定的差距,但两者均能够提供近似甚至高于传统P4法的固定稳定性,并能显著减少应力集中。故CBT置钉法能在理论上成为提供胸腰段爆裂性骨折稳定性的备选方案。

Objective：Cortical bone trajectory （CBT） method was applied to thoracic lumbar burst fracture through finite element analysis for verifing the feasibility of CBT application by simulation of biomechanical analysis. Methods： A case of adult male was simulated：（A） integrity state;（B） burst fracture state;（C） fixed state：（1） 4 pedicle screws cross segment and 2 rods（P4）;（2） 4 CBT screws （C4）;（3） 6 pedicle screws and 2 rods（P6）;（4） 6 CBT screws and 2 rods（C6）. Compare the total deformation and the equivalent stress of the corresponding internal fixation of nodes of those models. Results： Fractured model could get obvious immediate stability in four groups of internal fixation. Total deformation of fractured model and equivalent stress of internal fixation under each state generally increased in P4 group compared to the other models. Total deformation of fractured model and equivalent stress of internal fixation under each state of P6 group had obvious advantages than those in other groups. Total deformation of fractured model and equivalent stress of internal fixation under each state of C6 group were less than that in the C4 group. Conclusion： Both fixation of 4 CBT method and 6 CBT method had a certain gap between the P6 method, but could provide approximate even higher stability of fractured model than the traditional four pedicle screws method, and significantly reduced stress concentration of fixation. So, CBT nailing method can theoretically be an alternative to provide stability of thoracic lumbar burst fracture.