Feasibility of biomechanical strength in upper cervical fixation and analysis of these screw strength

为了实现安全有效的上颈椎固定手术，我们评估了我们发明的后弓螺钉(PAS)的拔出强度。后弓螺钉有足够的拔出强度。与经后弓技术(TAN)置入的C1侧块螺钉相比，差异无统计学意义，但PAS的强度明显强于经后弓入路的C1侧块螺钉(Uni-Harm)。Tan的拔出强度几乎等于PAS和Uni-Harms的总和。我们分析了使用C1侧块螺钉进行寰枢椎内固定的临床效果，重点比较了Tan和Uni-Harm两种不同的固定技术。总体结果令人满意，愈合率高，并发症发生率低等。然而，单一HAMS术后C2神经刺激发生率较高。我们还报告了日本人桥小脑桥的发生率。

We evaluated the pullout strength of posterior arch screw(PAS) that was our original invention to achieve safe and effective upper-cervical fixation surgery. Posterior arch screws had sufficient screw pullout strength. Compared to C1 lateral mass screw inserted via posterior arch technique(Tan), there was no statistical significance, however, PAS was statistically stronger than C1 lateral mass screw inserted directly technique(uni-Harms). The pullout strength of Tan was nearly equal to summation of PAS and uni-Harms.We analyzed clinical results of atlanto-axial fixation using C1 lateral mass screws, especially focused comparing two different techniques between Tan and uni-Harms. Overall results was satisfactory ; high union rate, low complication rate, etc. However, C2 nerve irritation was highly seen following uni-Harms.We also reported the incidence of Ponticulus Posticus in Japanese using plain computed tomography and plain X-ray films.