经皮长U形空心椎弓根钉系统治疗胸腰椎骨折的生物力学研究

Biomechanical evaluation of the long U-shaped hollow pedicle screw system for percutaneous fixation of thoracolumbar fractures

目的评价经皮长U形空心椎弓根钉系统内固定治疗胸腰椎骨折的生物力学性能。方法采集成年新鲜胸腰椎标本8具，平均分为普通椎弓根钉组和长U形空心椎弓根钉组，每组4具标本。制作椎体前厢压缩性骨折，分刖采用普通椎弓根钉和长U形空心椎弓根钉固定治疗，利用生物力学的电测试验应力分析方法测试固定后脊往的极限压缩强度、轴向压缩刚度、弯曲刚度、扭矩和扭转刚度=结果普通椎弓根钉组和长U形空心椎弓根钉组的平均极限压缩强度分别为（3450．02±110．03）、（3430．04±102．12）MPa，平均轴向压缩刚度分别为（407．52±33．02）、（395．04±26．46）N／mm，平均弯曲刚度分别为（305．14±26．53）、（295．12±23．80）N·cm／Deg，平均扭矩分别为（6．45±0．25）、（6。25±0．21）N·m，平均扭转刚度分别为（0．54±0．04）、（0．52±0．03）N·cm／Deg，以上项目两组间比较差异均无统计学意义（P〉0．05）。结论长U形空心椎弓根钉系统内固定胸腰椎骨折术后的生物力学性能与普通椎弓根螺钉接近，能满足骨折愈合的生物力学要求。

Objective To evaluate the biomechanieal characteristics of the long U-shaped hollow pedicle screw system for percutaneous fixation of thuracolumbar fi＇actures. Methods Models of vertebral cmnpression fracture were created bv flexion in 8 fresh cadaveric samples of thoracolumhar spine. The models were divided into 2 equal groups according to the fixation system applied. In group A conventional pediele screws were used while in group B hmg U-shaped hollow pedicle screws were used. The yield cmupressive strength, axial eompression stiffiless, bending stiffness, torque and torsional stiffness of all the fixated spines in the 2 groups were tested by the bio-meehanical electrical measurement and compared as well. Results The conventional pediele screws and long U-shaped hollow pedicle screws showed no significant differences re- garding yield compressive strength （3450.02 ± 110.03 MPa vs. 3430.04±102. 12 MPa）, axial compressinn stiffness（407.52±33.02 N/ram vs. 395.04± 26.46 N/mm）, bending stiffness （305. 14 ± 26. 53 N · cm/Deg vs. 295. 12±23.80N ·cm/Deg）, torqne （6.45±0.25 N · m vs. 6.25±0.21 N · m） or torsional stiffness （0.54 ±0.04 N · cm/Deg vs. 0. 52 ±0, 03 N · em/Deg） （ P 〉 0.05）. Conclusion The hmg U-shaped hollow pedicle screw system can satisfy the biomechanical requirements for fixation of thoracolumbar fractures and can fimctiml as well as the conventional pedicle screw system.