目的比较脊柱滑脱中两种后路固定方法中螺钉局部受力情况。方法采用6具新鲜成人尸体脊柱标本(L1-L5),Panjabi法制备腰椎滑脱模型,固定器械为SINO椎弓根钉及固定棒。应用电阻应变测量法及生物力学测量方法,通过INSTRON5567材料实验机对标本进行垂直压缩、前屈、后伸、左右侧屈5种状态的测试。实验分为二椎体固定组(A组)和三椎体固定组(B组)。结果二椎体固定组在垂直压缩、前屈、左右侧弯运动时提拉钉所受应力大于三椎体固定组(P<0.05)。结论三椎体固定时提拉钉根部所受应力小于二椎体固定,能够有效降低螺钉因疲劳产生应力集中而发生断裂的概率。

Objective To measure and compare the stresses along the screws in three-segment and two-segment posterior internal fixation in spondylolishesis.Method Six fresh samples of human lumbar vertebras were used in the study.The spondylolishesis model was made by Panjabi method,and was placed with the universal spine system of SINO.By strain measurement and biomechanical measurement,the samples were tested in 5 different directions with INSTRON 5567.Stress along the screws for two-segment(group A) and three-segment(group B) were measured respectively.Result The draw-screw in group A shared more stress than that in group B(P<0.05);The fixed-screw in group B shared more stress than in group A(P<0.05)?.Conclusion The three-segment internal fixation can effectively decrease the stress along the draw-screw,and depress the probability of breakage of the screw due to the system fatigue.