椎弓根钉固定与椎体成形术治疗爆裂型骨折的生物力学研究

Biomechanics of burst fractures treated with transpedicular screw fixation combined with vertebroplasty

目的：评价用椎弓根钉系统固定并同时经椎弓根人工骨椎体成形术治疗胸腰椎爆裂性骨折的生物力学效果，为临床术式选择提供生物力学依据。方法：采用12具国人新鲜脊柱标本（T11～L3），预损伤后压缩法模拟失去前柱支持，完全不稳的L。椎体爆裂性骨折。实验分完整状态组、椎弓根钉固定组和椎弓根钉固定并椎体成形术组。测试标本前屈，后伸，左、右侧弯及左、右轴向旋转状态下固定节段（T11-L3）的运动范围（ROM）以及极限载荷，并计算刚度，进行统计学处理，比较各组间差异。结果：椎弓根钉固定并椎体成形术与单纯椎弓根钉固定两种手术方式进行比较，在屈伸、左右侧弯时，二者运动范围之间的差异无统计学意义，而在轴向旋转时，前者[左旋：（72．42±16．33）％，右旋：（70-30±11．58）％]运动范围小于后者[左旋：（106．92±12．01）％，右旋：（105．02±14．31）％]（P〈05）。极限载荷和刚度之间比较，前者均大于后者（P〈0．05）。结论：采用椎弓根钉固定并椎体成形术治疗胸腰段爆裂型骨折，能够提高生物力学稳定性，稳定效果要优于单纯的后路短节段椎弓根螺钉内固定，同时也可以增加固定节段承受的极限载荷和刚度。

Objectives： To estimate the biomechanical effects of transpedicular screw fixation combined with percutaneous vertebroplasty on thoracolumbar burst fractures. Methods： Twelve fresh cadaveric spines were dissected from T11-L3 and performed the models of unstable L1 burst fracture without anterior column supporting, adopting compression method after pre-injury. The models were divided into the following groups： intact, transpedicular screw fixation alone and transpedicular screw fixation combined with percutaneous vertebroplasty. The range of motion （ROMs） and the displacement during flexion, extension, lateral bending, and axial torsion of T11-L3 segments were measured with the six-freedom degree robotics system controlled by mixed force under material test machine and analyzed. Results： To compare the biomechanical effects of transpedicular screw fixation combined with percutaneous vertebroplasty and.transpedicular screw fixation alone, the ROMs under axial rotation of the former were smaller than that of latter （P〈0.05）, however, there was no statistical significance between them under the loading of flexion, extension or lateral bending. The extreme loading and stiffness of the former were higher than that of latter （P〈0.05）. Conclusions： Transpedicular screw fixation combined with percutaneous vertebroplasty offers an improved biomechanical stability, extreme loading and stiffness compared to simple transpedicular screw fixation for treating thoracolumbar burst fracture.