三种后路内固定手术治疗胸腰段骨折的生物力学对比

目的比较椎弓根螺钉经伤椎短节段、经伤椎三节段与跨伤椎长节段三种固定状态治疗胸腰段骨折的生物力学差异。方法选取新鲜家猪脊柱标本(T_(13)～L_5)16具,随机数字表法分为正常组、经伤椎短节段组、经伤椎三节段组和跨伤椎长节段组各4具,除正常组外均制备为L_2椎体爆裂性三柱骨折模型,而后使用椎弓根螺钉分别模拟经伤椎短节段固定、经伤椎三节段固定及跨伤椎长节段固定三种状态。使用脊柱三维运动试验机在四组模型上模拟人体脊柱前屈、后伸、侧屈和旋转活动,比较不同运动状态下四组伤椎上下相邻节段的运动范围(range of motion,ROM)及不同载荷下四组标本的轴向压缩刚度。结果经伤椎三节段组与跨伤椎长节段组在前屈[(1.19±0.27°)vs.(1.29±0.48)°]、后伸[(1.13±0.34)°vs.(1.02±0.46)°]、左右侧屈[(2.01±0.66)°vs.(1.94±0.61)°]及左右旋转[(2.48±0.50)°vs.(2.59±0.48)°]的ROM上差异均无统计学意义(P0.05);经伤椎三节段组与经伤椎短节段组在前屈[(1.19±0.27)°vs.(2.50±0.41)°]、后伸[(1.13±0.34)°vs.(1.70±0.44)°]、左右侧屈[(2.01±0.66)°vs.(3.44±0.85)°]及左右旋转[(2.48±0.50)°vs.(3.24±0.65)°]的ROM前者显著低于后者,差异均有统计学意义(P0.05)。经伤椎三节段组与跨伤椎长节段组的轴向压缩刚度[(194.12±99.83)N/mm vs.(238.36±96.01)N/mm)]差异无统计学意义(P0.05);经伤椎三节段组的轴向压缩刚度显著高于经伤椎短节段组[(194.12±99.83)N/mm vs.(157.91±52.87)N/mm)],差异有统计学意义(P0.05)。结论对于胸腰段爆裂性三柱骨折,经伤椎三节段固定与跨伤椎长节段固定均可获得良好的力学稳定性,但前者椎体固定数量少于后者,脊柱活动度更佳,值得临床推广。

Comparison of biomechanics among three different internal fixation operations in thoracolumbar fractures

Objective To compare the biomechanics data among three different internal fixation operations in thoracolumbar fractures. Methods Thirty-two cases of fresh pig spinal specimens(T13-L5) were selected and randomly divided into normal group(4 cases),transvertebral short segment group(4 cases),three segments group(4 cases) and long segment group(4 cases).They were made into thoracolumbar fractures models and corresponding internal fixation except the normal group.The axial compression stiffness and range of motion(ROM) of flexion,extension,lateral flexion and rotation were compared among the four groups. Results There was no significant difference in the ROM of flexion[(1.19±0.27)°vs.(1.29±0.48)°],extension[(1.13±0.34)°vs.(1.02±0.46)°],lateral flexion[(2.01±0.66)°vs.(1.94±0.61)°] and rotation[(2.48±0.50)°vs.(2.59±0.48)°] between the three segments group and the long segment group(P>0.05);the ROM of flexion[(1.19±0.27)°vs.(2.50±0.41)°],extension[(1.13±0.34)°vs.(1.70±0.44)°],lateral flexion[(2.01±0.66)°vs.(3.44±0.85)°] and rotation[(2.48±0.50)°vs.(3.24±0.65)°] in the three segments group were lower than those of the transvertebral short segment group(P<0.05).There was no significant difference in axial compression stiffness between the three segments group and the long segment group[(194.12±99.83) N/mm vs.(238.36±96.01) N/mm,P>0.05];the axial compression stiffness of the three segments group was higher than that of the transvertebral short segment group[(194.12±99.83) N/mm vs (157.91±52.87) N/mm,P<0.05]. Conclusion Both three segments fixation and long segment fixation show excellent spinal stability in burst thoracolumbar fractures.However, three segments fixation fixes less vertebrae with more flexibility.