前路经寰枢关节螺钉内固定术治疗创伤性寰-枢椎不稳的前期研究

A preliminary study of anterior C 1～2 transarticular screw for traumatic instability of C 1～2 joint

目的：提出一种治疗创伤性寰枢椎不稳的新手术方法——前路经寰枢关节螺钉内固定术，并通过建立模拟手术模型和评价安全性，验证其临床应用的可行性。方法：在１７具人体标本的术前颈椎Ｘ线片上作５条辅助线，取右侧颌下切口，根据术前计划，经枢椎椎体－寰枢关节－寰椎侧块方向置入螺钉。在术后Ｘ线片上测量螺钉轨道参数，与术前计划参数作ｔ检验。在经寰椎横突上、下缘及枢椎上关节面下缘三个横断面上测量螺钉与椎动脉的距离。统计椎动脉、脊髓及枕颈关节损伤的例数。结果：①术前计划参数：内界角１８°±１．４°，外界角３３°±３．７°，标准外偏角２６°±２．９°，后界角３９°±４．１°，标准后倾角２４°±２．０°。②螺钉轨道实际外偏角２４°±３．５°，实际后倾角２７°±４．０°，与术前参数比较无显著性差异（Ｐ＞０．０５）。③在经枢椎上关节面下缘的横断面上螺钉与椎动脉距离最短，平均值６ｍｍ，最小值３．５ｍｍ，无椎动脉及脊髓损伤，２例枕颈关节损伤。结论：前路经寰枢关节螺钉内固定术与后路内固定术互为补充。经应用解剖研究证明其具有较高的安全性和较大的临床实用性。

Objective:A new method of anterior C 1～2 transarticular screw for traumatic instability of C 1～2 joint was studied experimentally.The feasibility is testified by surgical model and security evaluation.Method:17 formalin preserved human specimen were obtained for simulating operation.5 auxiliary lines were drawn in X ray film.Through submandibular incision of right side,screws were drived from C 2 vertebral body through atlantoaxial joint into C 1 lateral mass.Postoperative X ray films were taken.The difference of screw trajectory between preoperative and postoperative measurement were compared by t test.The specimen were transected at three levels,the shortest distance between screws and vertebral artery in every level was measured.Result:(1)The data in preoperative plan are:medial limit angle 18°±1.4°,lateral limit angle 33°±3.7°,ideal lateral angle 26 °±2.9°, posterior limit angle 39°±4.1°,ideal posterior angle 24°±2.0°.(2)The actual lateral angle 24°±3.5°,actual posterior 27°±4.0°.No significance existed between pre and post operative measurement.(3)The average shortest distance between screw and vertebral artery was 6mm with minimal value for 3.5mm.Neither vertebral artery nor spinal cord was injured.Two occipito atlanto joints were injured.Conclusion:The preliminary study showed feasibility and security of the new technique.It can be a substitution of posterior fixation methods when contraindication existed. Authors address\ Orthopedics Department,the Third Hospital of Chengdu,Sichuan,610031