Hangman骨折后路短节段内固定术固定螺钉拔出力研究

Experimental study of screw pull-out strength of posterior cervical oligo-segmental fixtion for treament of Hangman's fracture

目的:对Hangman骨折后路短节段内固定术固定螺钉进行拔出力研究,为螺钉固定方式的选择提供依据。方法:利用6例新鲜的枢椎和第3颈椎标本进行单层皮质骨和双层皮质骨的C2椎弓根螺钉、峡部骨折状态C2椎弓根螺钉、C3侧块螺钉固定及C2、C3椎体螺钉固定,测试螺钉拔出强度并进行统计学分析。结果:C2双皮质椎弓根螺钉拔出力最大(1726.5±433.3)N;C2单皮质椎弓根螺钉(1279.9±432.0)N和Hangman骨折双皮质螺钉(959.6±253.2)N无显著性差异,拔出力明显强于Hangman骨折单皮质螺钉(586.3±118.9)N和C3双皮质侧块螺钉拔出力(717.5±166.9)N,后两者无统计学差异。C3单皮质侧块螺钉(487.3±171.6)N和C2椎体螺钉(392.2±109.8)N、C3椎体螺钉(397.3±98.5)N之间无统计学差异。结论:Hangman骨折后路短节段内固定螺钉是可靠的;临床应用C2椎弓根螺钉和上下节段联合固定时单皮质固定足够,Hangman骨折时以双皮质固定为佳。

Objective： To evaluate the screw pull-out strength of posterior cervical oligo-segmental fixtion for treament of Hangman＇s fracture, and provide biomechanical basis for clinical choice of screw fixtion technique. Methods： In 6 flesh adult human cervical specimens, the unicortical and bicortical screw were placed on intact or Hangman＇s fracture C2 pedicle and C3 lateral mass. The vertebrae screw were placed on C2 and C3 separately, and the pull-out strength was tested and compared. Results： The bicortical C2 pedicle screw got the strongest pull-out strength（1726.5±433.3N）, however, that of unicortical C2 pedicle screw（1279.9±432.0N） and bicortical Hangman＇s fracture C2 pedicle screw（959.6±253.2N） had no statstatistical difference, stronger than unicortical Hangman＇s fracture C2 pedicle screw （586.3±118.9N）and biocortical C3 lateral mass screw（717.5±166.9N）. The pull-out strength of C2, C3 vertebrae screw and unicortical C3 lateral mass screw has no statstatistical difference.Conclusion： The screw pull-out strength of posterior cervical oligo-segmental fixtion for treament of Hangman＇s fracture is strong and safe. The tmicortical C2 pedicle screw is strong enough for fixtion, but its more reliable to take bicortical fixtion on Hangman＇s fracture C2 pedicle.