寰枢椎后路悬臂樑支撑线缆牵拉复位固定的生物力学稳定性评价

背景:目前治疗齿状突骨折致寰枢椎脱位的内固定方式多种多样,但均强调固定前复位,尚无一种既有满意的生物力学稳定性,又有较好的术中复位能力的内固定方式。目的:分析后路悬臂樑支撑线缆牵拉复位固定技术这一新的内固定方式的生物力学性能。方法:取12具新鲜尸体寰枢椎骨韧带标本,制成齿状突Anderson2型骨折试验模型,对每一标本先后行Brooks钛缆固定、Magerl螺钉固定、双侧寰枢椎侧块螺钉+枢椎椎弓根螺钉固定和悬臂樑支撑线缆牵拉复位固定,在1.5Nm载荷下模拟人体的寰枢椎三维运动,并用三维扫描仪对寰枢椎的三维运动范围进行测量。结果与结论:在1.5Nm载荷作用下,经后路悬臂樑支撑线缆牵拉复位内固定的寰枢椎前屈、左右侧弯范围均小于其他各组(P<0.05);后伸范围大于Magerl螺钉固定组(P<0.05),小于Brooks钢丝固定和钉棒固定组(P<0.05);左右旋转范围与Magerl螺钉固定组无差异(P>0.05),但小于Brooks钢丝固定组和钉棒固定组(P<0.05)。结果可见后路悬臂樑支撑线缆牵拉复位固定的三维稳定性优于双侧寰枢椎侧块螺钉+枢椎椎弓根螺钉固定和Brooks钛缆固定;仅在后伸方面稳定性不及Magerl螺钉。

The biomechanical stability of cable dragged reduction and cantilever beam internal fixation by posterior atlantoaxial approach

BACKGROUND:There are many methods of internal fixation for atlantoaxial dislocation caused by odontoid fractures,but all of them emphasize reset before fixation,so there is no a internal fixation both with satisfactory biomechanical stability and better intraoperative reset ability.OBJECTIVE:To evaluate the biomechanical properties of cable dragged reduction and cantilever beam internal fixation via posterior approach for upper cervical spine stability.METHODS:Occipitocervical spine specimens from twelve fresh human cadaveric were selected to establish fracture test model of odontoid Anderson type 2 which were mounted in a spine-testing machine to record the three-dimensional angular movement under 1.5 N m load.The specimens were fixed by Brooks titanium cable,Magerl screws,the lateral mass screws in the atlas+axial pedicle screw and cable dragged reduction and cantilever beam.RESULTS AND CONCLUSION:Under 1.5 N m load,the range of motion(ROM) during flexion and side bending of cable dragged reduction and cantilever beam internal fixation group were significantly smaller than those of other groups(P < 0.05).The ROM during in extension of cable dragged reduction and cantilever beam internal fixation group was significantly larger than that of Magerl screws fixation group(P < 0.05),but which was smaller than that of the Brooks titanium cable and pedicle screw fixation groups(P < 0.05).The ROM during rotation of cable dragged reduction and cantilever beam and Magerl screws fixation groups had no difference(P > 0.05),but which was smaller than that of the Brooks titanium cable and pedicle screw fixation groups(P < 0.05).The results indicated that stability of cable dragged reduction and cantilever beam internal fixation via posterior approach are better than the other groups,but which was only lower than Magerl screws fixation in the stability of the extension.