胸腰椎骨折伤椎短椎弓根钉固定的生物力学研究

Biomechanical study of unilateral fractured vertebral pedicle short-screw fixation in treatment of thoracolumbar fracture

[目的]通过生物力学测试对胸腰椎爆裂性骨折伤椎单侧短椎弓根钉固定的稳定性及刚度进行评价。[方法]取18具新鲜小牛胸腰段(T11～L3)标本,制作成胸腰椎爆裂性骨折模型,测试跨节段4枚椎弓根钉固定(4钉组)、伤椎单侧短椎弓根钉固定(5钉组)、伤椎双侧椎弓根钉固定(6钉组)标本模型的轴向压缩刚度及三维6个方向的运动范围(ROM)。[结果]4钉组、5钉组、6钉组三种固定方式,均能提高骨折模型的稳定性及刚度;5钉组、6钉组模型刚度均明显高于4钉组,差异有统计学意义(P<0.05),5钉组、6钉组模型在屈伸、侧弯、旋转6个方向的运动范围(ROM)均明显低于4钉组,差异有统计学意义(P<0.05);而5钉组与6钉组模型之间的刚度比较差异无统计学意义(P>0.05),5钉组与6钉组模型在屈伸、侧弯、旋转6个方向的运动范围(ROM)的比较差异无统计学意义(P>0.05)。[结论]对于胸腰椎爆裂性骨折,伤椎置钉固定能明显提高脊柱的刚度及稳定性,经伤椎单侧短椎弓根钉固定与伤椎双侧椎弓根钉固定对脊柱刚度及稳定性的影响无明显差异。

[ Objective ] To evaluate biomechanism on the unilateral short -screws fixation at the level of the fractured ver- tebra for thotacolumbar fractures. [ Method] Eighteen calf thoracolumbar spine specimens involved five vertebrae segement（T11 - L3 ） were obtained and made into the burst fracture specimens to compare the stability of three kinds of transpedicular fixations by its axial compression, bending, rotation and axial extraction force of the pedical screw. [ Result] The three kinds of transpe- dicular fixations（fixed with 4,5 or 6 pedical screws）could enhance the stability of injured thoracolumbar vertebrae. No statisti- cal difference of spine stability capacity was found between unilateral vertebral pedicle screw fixation （fixed with 5 pedicle screws） and bilateral vertebral pedicle screw fixation （ fixed with 6 pedicle screws） （ P 〉 0.05 ） , and both of them had statistical difference with short segment pedicle screw fixation （ fixed with 4 pedicle screws） （ P 〈 0.05 ）. [ Conclusion ] The stability of u- nilateral fractured vertebral pedicle screw fixation is better than short segment pedicle screw fixation. There is no statistical difference of spine stability capacity between unilateral fractured vertebral short pedicle screws fixation and bilateral fractured vertebral pedicle screw fixation.