寰枢椎后路经关节螺钉内固定治疗寰枢椎不稳定的生物力学及临床研究

目的评价寰枢椎后路经关节螺钉内固定术两种不同钉道的生物力学稳定性及疗效。方法在8例新鲜尸体标本依次轮流测试正常、Ⅱ型齿状突骨折行AO进钉点与改良进钉点两种后路钉道螺钉固定术模型三维运动范围，并在16例寰枢椎不稳定患者，采用枢椎下关节突下缘正中点为进钉点的方法行经关节螺钉固定及自体颗粒样松质骨植骨术。结果两种入钉方法均能明显减少寰枢关节的各向运动角度（P〈0．01），但两者间差异无统计学意义（P〉0．05）。经5～48个月随访，16例患者寰枢关节稳定性均获得恢复与骨融合，无并发症。结论新入钉点解剖标志明确。钉道长，能提供牢固地固定，并发症发生率低。

Biomechanical and clinical study of atlantoaxial instability in posterior atlantoaxial transarticular screw fixation

Objective To determine the biomechanical stability of C1-2 and clinical effects after instrumentation with two screw trajectory in posterior atlantoaxial transarticular screw fixation. Methods The three-dimensional motions of C1 relative to C2 were measured in 8 human cadaveric specimens, which was by turns under 4 models: nomal, II odontoid fractures, with AO or modified posterior atlantoaxial transarticular screw fixation respectively. The 16 atlantoaxial instability patients were treated with posterior C1-C2 transarticular screws and the autogenous granulated cancellous bone graft, in which the screw entry point was the center of lower edge on axis processus articularis inferior. Results Two inserting methods of posterior atlantoaxial transarticular screw fixation significantly decreased motion in all directions. There was generally no significant difference in the amount of motion among the two screw trajectory. During a follow-up of 5-48 months, atlantoaxial instability was restored satisfactorily in 16 patients with no complication and bone fusion was obtained. Conclusion The bony landmark of the new entry point was definite, which can provide the long length of screw trajectory and the rigid fixation with low complication rate.