脊柱椎弓根螺钉内固定效果的生物力学评价

E VALUTION OF INTERMAL FIOATIVE EFFECT FOR PEDICULAR SCREW IN BIOMECHANICE

目的：为探讨椎弓根螺钉与椎体骨质之间的固定关系，为临床上椎弓根螺钉的改进与固定提供科学依据。方法：采用三维有限元素法，对5种不同的椎弓根螺钉的固定效果进行评估，并进行了9付新鲜胸腰节段标本的拔出力试验和界面应力测试。结果：RF、UT、Steffee、Dick钉等拔出力，界面剪切应力呈显著性差异，（P＜0．01），提示影响椎弓根螺钉固定效果的主要因素有：螺钉的结构形态、螺纹参数、骨密度，手术时螺钉的拧紧力矩大小，以及进钉的深度等。结论：根据不同病例适当增加螺钉的外径，加深螺距与导程，对增强固定效果是必要的。

Aim To seek the fixative relation between the pedicular Screw and the verterbral bodies and to furnish the basis of the improve for pedicular screw. Methods: the five not alike pedicular screw were evaluted With three dimensional limited element method. The pullout test and boundary surface stree measure were taken on the specimens of 9 cadaverice thareco Lumbar Result:the pullout power and boundary surface shearing stress of RF. UT, steffee, Dick, et al, were remarkabl difefrent(p<0.01) It was explain for heinfluence factors of the pedicular screw fixation were the shape,screw parameter, bone density and tightening up pitching moment. Conclusion: It was nessesery to increase the external diameter. deepen and the Length of pedicular screw according to the differece patients.