寰枢椎后路“三点式”经椎弓根固定的生物力学评价

The biomechanical evaluation of atlantoaxial instrumentation by three-point pedicle screw technique

目的:评价寰枢椎后路椎弓根钉棒系统"三点式"固定方法的生物力学稳定性。方法:采用6具新鲜人体颈椎标本制作6种状态,分别为正常组(A组)及失稳后固定组,用磨钻切除寰椎前弓约1.5cm,用摆锯于基底部切断齿状突,切断寰枢间所有韧带,切开寰枢侧块关节囊后半部分制成寰枢椎失稳的模型,再根据不同的固定方式将失稳后固定组分为Brooks钢丝固定组(B组)、左侧C1～C2椎弓根螺钉固定组(C组)、C1双侧椎弓根螺钉+C2左侧椎弓根螺钉棒固定组("三点式"固定,D组),C1左侧椎弓根螺钉+C2双侧椎弓根螺钉棒固定组("三点式"固定,E组)、双侧C1～C2椎弓根螺钉棒固定组(F组)。在脊柱三维运动仪上依次测量6种状态下寰枢椎间的屈伸、侧屈、旋转运动范围并利用统计学方法评价其稳定性。结果:在各个运动方向上,各种内固定组的运动范围均小于正常组(P<0.05),D、E组间无差异(P>0.05);在屈伸、左/右旋转、右侧屈时,D、E组的稳定性与F组间无差异(P>0.05),均优于B组及C组(P<0.05);在左侧屈时,D、E组的稳定性不如F组(P<0.05),但优于C组及B组(P<0.05)。结论:"三点式"固定具有可靠的三维稳定性,能够满足寰枢椎不稳临床治疗的要求。

Objective：To evaluate the biomechanical stability of three-point pedicle screw technique for at-lantoaxial instrumentation.Method：Six fresh human cadaveric cervical spines（C0-C5）（age,25-36 years） were used.After testing the intact spines （group A）,instability was induced by removing the anterior arch of atlas, transverse and alar ligaments and posterior capsule of atlantoxial joints.Then the instable spines were subject-ed to the following five different techniques,Brook wire fixation technique （group B）,C1-C2 left pedicle screws fixation （group C）,C1 bilateral pedicle screws and C2 left pedicle screw fixation （group D）,C1 left pedicle screw and C2 bilateral pedicle screws fixation（group E）,C1-C2 bilateral pedicle screws fixation（group F）.Range of motion at C1-C2 was measured at each specimen on six loading directions through spinal flexi-ble motion testing system.The data were analyzed using SPSS software.Result：All 5 techniques significantly decreased range of motion of C1-C2 compared with the intact spine （P0.05）.There was no statistical differ-ence between group D and group E（P0.05）.There was no statistical difference among group D,E,F（P0.05） in flexion/extension,axial rotation and right lateral bending,however they showed superior to group B and C （P0.05）.As for left lateral bending,group D or E demonstrated a trend toward increasing range of motion compared with group F （P0.05）,but still superior to group B and C （P0.05）.Conclusion：Fixation of at-lantoaxial complex using three-point pedicle screw technique can provide reliable stability,which can be used in clinical practice.