下颈椎后路内固定器对失稳颈椎固定作用的生物力学评价

目的 评价下颈椎后路内固定器重建失稳颈椎稳定性的生物力学性能。方法 5具新鲜颈椎尸体标本制造脱位模型后依次用棘突钢丝、侧块螺钉、自制螺钉、椎弓根螺钉固定，用脊柱三维运动测量系统测算其运动范围。结果 棘突钢丝在屈伸和侧弯时的运动范围可恢复完整颈椎水平，但旋转时的运动范围比完整颈椎大。侧块螺钉和自制螺钉的运动范围均较完整颈椎小，且侧弯和旋转的运动范围明显小于棘突钢丝。椎弓根螺钉侧弯和旋转的运动范围最小。内固定相邻节段的运动范围虽有变化，但差异无显著性(P＞0．05)。结论 棘突钢丝可重建失稳颈椎的屈伸稳定性，但侧弯和旋转稳定性欠佳，侧块螺钉和自制螺钉优于棘突钢丝，椎弓根螺钉的稳定性最强。

Biomechanical evaluation of lower cervical spine with posterior fixations

Objective To evaluate the ability of different posterior lower cervical fixations to reconstruct the stability of unstable cervical spine.Methods After discoligmentous injury,5 fresh cervical spine samples were fixed with process wire,lateral mass screw plating,self-designed lateral mass screw system,transpedicular screw plating and were analyzed by three dimensional motions.Results The range of motion (ROM) of process wire was less than that of the intact in flexion,extension,lateral bending,but not in axial rotation.The ROM of lateral mass screw plating and self-designed lateral mass screw system were less than that in the intact,and less than that of the process wire in lateral bending and axial rotation.The ROM of transpedicular screw plating was the smallest in lateral bending and axial rotation.The changes of ROM of adjacent segments of fixations were not significant.Conclusion The process wire can restore stability in flexion and extension,but was not strong enough in lateral bending and axial rotation.The lateral mass screw plating and the self-designed lateral mass screw system were stronger than the process wire,and the transpedicular screw plating was the strongest.