枢椎后路侧块螺钉与椎弓根螺钉固定强度的生物力学评价

Biomechanical evaluation of the pull-out strength of posterior C2 lateral mass screw and pedicle screw fixation

目的评价单皮质和双皮质枢椎侧块螺钉与枢椎椎弓根螺钉的固定强度,为临床选择枢椎后路螺钉的固定方式提供生物力学依据。方法利用12具新鲜尸体枢椎标本,进行单皮质和双皮质的椎弓根螺钉或侧块螺钉固定,测试比较其螺钉拔出强度。结果双皮质枢椎椎弓根螺钉的拔出力量最大,为(1 726.5±433.3)N;单皮质枢椎椎弓根螺钉〔(1 279.9±432.0)N〕与双皮质枢椎侧块螺钉〔(1 054.8±411.3)N〕之间差异无统计学意义;单皮质枢椎侧块最小为(689.4±128.0)N。结论枢椎后路螺钉固定宜首选椎弓根螺钉,侧块螺钉可作为补充固定技术,且以双皮质骨固定为宜。

Objective To evaluate the screw pull-out strength of posterior C2 when the screw is fixed to C2 through the lateral mass or transpedicle unicortically or bicortically, so as to provide biomechanieal basis for the clinical application of posterior C2 screw fixation technique. Methods The lateral mass screw or the pedicle screw was separately anchored into 12 fresh C2 specimens unicortically or bi- cortically. The screw pull-out strength of different fixation was tested and compared with the others. Results The average pull-out strength of C2 bicortical pedicle screw was （ 1726.5±433.3 ） N, the strongest during all the methods. The mean pull-out strength of C2 unicortical pedicle screw and C2 bicortical lateral mass screw were （ 1279.9±432.0） N and （ 1054.8±411.3） N, respectively, with no statistical difference. The pull-out strength of unicortical C2 lateral mass screw was the lowest, ie, （689.4±128.0） N. Conclusion Pedicle screw should be the first choice for the posterior fixation on axis. C2 lateral mass screw fixation can be another supplement choice and the screw had better be placed bicortically.