膨胀式椎弓根螺钉脊柱后路内固定的生物力学测试

目的　测试并比较自行设计的膨胀式椎弓根螺钉 (expansivepediclescrew ,EPS)与USS ,Tenor ,CDH椎弓根螺钉的最大轴向拔出力 ,评价EPS螺钉的椎弓根固定作用。方法　将 6 0个新鲜小牛腰椎随机分成 3组 ,每组 2 0个椎体(4 0侧椎弓根 ) ,每组均随机在一侧拧入EPS螺钉 ,对侧则分别拧入USS ,Tenor ,CDH螺钉 ,进行螺钉拔出实验 ,测试并记录最大轴向拔出力。结果　EPS ,USS ,Tenor ,CDH螺钉的最大轴向拔出力分别为 2 6 5 8 4N± 816 7N ,192 9 9N±4 84 9N ,184 9 8N± 5 75 9N ,1980 9N± 836 4N。EPS螺钉和其它三种螺钉的最大轴向拔出力相比均有非常显著差异 (P <0 0 1)。结论　EPS螺钉较目前使用的USS ,Tenor ,CDH非膨胀椎弓根螺钉有更好的固定作用。

Biomechanical Evaluation of an Expansive Pedicle Screw in Calf Vertebrae

Objective To measure and compare the pullout strength of newly-designed expansive pedicle screws with that of USS,Tenor,and CDH pedicle screws in calf lumber spine, and to evaluate the screw purchase of EPS screws. Methods Sixty fresh calf lumber vertebrae harvested from 12 calf lumber spine were randomly divided into 3 groups, i.e. 40 pedicles from 20 vertebrae for each group. EPS screws were randomly inserted into one side of pedicles of all vertebrae, while USS, Tenor and CDH screws were inserted into the opposite pedicles for pullout test, respectively. The maximum axial pullout strength was used for comparison. Results The maximum axial pullout strength of the EPS, USS, Tenor and CDH screws were 2658.4N±816.7N,1929.9N±484.9N,1849.8N±575.9N and 1980.9N±836.4N, respectively. The maximum axial pullout strength of EPS screws was statistically significantly greater than that of USS, Tenor and CDH screws ( P <0.01). Conclusions Results suggested that as compared with USS, Tenor and CDH screws, the expansive pedicle screws might have better fixation effects.