不同骨质疏松程度下椎弓根螺钉强化固定的生物力学研究

目的 探讨在不同骨质疏松程度下多种脊柱固定方式对脊椎的固定效果.方法 取新鲜猪脊柱16具（共96节椎体）.用随机区组分为Ⅰ,Ⅱ,Ⅲ 3个区组,A,B,C,D 4个处理组.用EDTA-Na2脱钙处理2,3,4周后,A组：单纯行普通椎弓根钉固定;B组：钉道强化后普通椎弓根钉固定;C组：椎体强化后普通椎弓根钉固定;D组：空心椎弓根钉＋骨水泥固定.骨水泥凝固后行最大轴向拔出力和最大旋出力矩测试.结果 最大轴向拔出力和最大旋出力矩Ⅰ,Ⅱ组：B组高于A组;C组及D组高于B组;C组和D组比较差别无统计学意义.Ⅲ组：B,C,D组高于A组,B,C,D组之间差别无统计学意义.结论 椎弓根螺钉强化固定在一般骨质疏松脊柱上的效果明显,而在严重骨质疏松脊柱的效果下降.

Biomechanical Analysis of Vertebral Pedicle Screws Fixation after Augmentation with Bone Cement on Different Grades of Vertebral Osteoporosis

Objective To study the biomechanical effect of Vertebral Pedicle Screw Fixation ＇after several kinds of Fixation on different grades of vertebral osteoporosis. Methods Ninety-six fresh pig lumber vertehraes from 16 spines（96 vertebraes in total） ,which were classified into 3 blocks（ Block Ⅰ -Ⅲ ） and 4 groups（ Group A-D） by randomized block design,were decalcified by EDTA-Na2 for weeks. After bone mineral density was determined fimr fixation methods were applied. Common pedicle screws were implanted on vertebraes in Group A; Filled with PMMA in the pediele tracks,common pedicles screws then were implanted in Group B;Augmentation by injecting PMMA into vertebral body were applied on vertebraes in Group C ;Screws with hollow lateral holes enhanced by PMMA would be used in Group D. The maxi- mum axial pullout strength and rotational torque were recorded after PMMA completely solidified. Results Means of Fmax and rotational torque of Group C and D,both of which had no statistical difference,were significantly higher than that of Group A anti B in Block Ⅰ and Ⅱ. There were no difference in biomechanical test result between Group B,C, D in Block Ⅲ ,which were higher significantly than group A. Conclusion Effect of augmentation of vertebral pedicle screws was more significant in common osteoporosis than that in serious osteoporosis.