经口寰枢椎复位内固定钢板-Ⅲ系统在复杂寰枢椎脱位中的应用

目的 评估经口寰枢椎复位内固定钢板(transoral atlantoaxial reduction plate,TARP)-Ⅲ系统设计的生物力学特点及其临床应用疗效.方法 在TARP-Ⅱ的基础上设计改良TARP-Ⅲ:将钢板的枢椎螺孔向上向内各移1～2 mm,使固定的枢椎椎体钉改成椎弓根钉固定或关节突钉固定;将钢板的螺孔增设一个可万向活动的自锁环和万向导钻;进行枢椎三种螺钉固定的抗拔出力试验;并将TARP-Ⅲ应用于44例复杂难复性寰枢椎脱位患者.枢椎采用经口椎弓根固定或关节突固定.结果 (1)枢椎三种螺钉固定的最大拔出力分别为:枢椎前路椎弓根螺钉(593.1±97.8)N、枢椎关节突螺钉(469.9±73.3)N和枢椎椎体螺钉(395.2±75.1)N.结果 显示,三种固定方式的最大拔出力进行两两比较,差异有统计学意义(P＜0.05).(2)临床应用44例,获得5～38个月随访,平均18个月,观察寰枢复位、寰枢节段椎管减压,神经功能恢复及并发症的情况.本组有36例达解剖复位,8例接近解剖复位,脑干脊髓角基本纠正,颈髓均得到充分减压.按尹氏颈髓受压减压效果评估方法 评估,颈髓减压改善率平均88.2%.脊髓功能按日本骨科学会(JOA)评分,脊髓功能平均改善率达76.6%.结论 TARP-Ⅲ及其枢椎椎弓根钉或关节突钉固定的生物力学等性能明显优于TARP-Ⅱ的枢椎椎体钉固定,加之钢板螺钉和螺钉的万向自锁机制的设计使之更加完善,经临床应用疗效显著.

Abstract：

Objective To evaluate the biomechanical characteristics and the clinical advantage of transoral atlantoaxial reduction plate(TARP)Ⅲ.Methods Design of TARP-Ⅲ was based on TARP-Ⅱ.The screw hole in the axis was moved 1-2 mm upwards and inwards in a plate which turned a vertebral screw into a pedicle screw or an articular process screw.A polyaxial self-lock ring and polyaxial guiding drill were added to the crew hole of the plate.Finally,the withdrawal resist ence force of the three axis screws was tested and TARP-Ⅲ was used in 44 patients with complicated irreducible atlantoaxial dislocation.The axis was fixed with the pedicle screw or the articular process screw.Results The maximum withdrawal resist ence force of the anterior pedicle screw,the articular process screw and the vertebral screw in the axis was(593.1 ± 97.8)N,(469.9 ± 73.3)N and(395.2 ± 75.1)N respectively,with statistical difference between groups among three fixation methods(P ＜ 0.05).All 44 patients were followed up for 5-38 months(average 18 months),which showed complete anatomic reduction in 36 patients and appropriate anatomic reduction in eight,with basic correction of the angles between the brain stem and the spinal cord and sufficient decompression of the spinal cord.The decompression rate of the cervical spinal cord was average 88.2% according to the Yin evaluating method of cervical cord decompression.The improvement rate of spinal cord function was average 76.6% according to Japanese Orthopaedic Association(JOA)score.Conclusion With the design of polyaxial self-lock mechanism,TARP-Ⅲ with the pedicle screw or the articular process screw surpasses TARP-Ⅱ with vertebral screw in aspect of biomechanics.