BACKGROUND:With the development of atlantoaxial morphology, applied anatomy and biomechanics, pathogenesis, diagnosis and treatment of atlantoaxial instability have attracted more and more attention. However, the development of effective fixation for atlantoaxial instability is relatively late, so scholars al over the world have made numerous studies. OBJECTIVE:To compare biomechanical functions of different fixations through atlantoaxial posterior approach, and to assess its stability. METHODS:We retrieved recent studies on comparative biomechanical evaluation and its primary clinical application of different posterior approaches in repair of atlantoaxial instability, and conducted a retrospective analysis by measuring the three-dimensional range of movement in normal atlantoaxial complex and atlantoaxial instability models. This analysis evaluated the stability of different fixations under normal three-dimensional atlantoaxial movement, and provided a biomechanical basis for reasonable fixator selection. RESULTS AND CONCLUSION:Atlantoaxial posterior fixation included Gal ie wire fixation, Brooks fixation, Apofix and Halifax vertebral plate hook fixation, screw fixation through joint and atlantoaxial pedicle nail/rod fixation. Gal ie technique contributes to the reduction of anterior semiluxation, but its mechanical stability is poor. Brooks technique has strong rotation and stretch forces. Apofix and Halifix vertebral plate hook device provides strong anti-rotation and anti-antelocation strength, and is more stable than Gal ie technique in mechanics. The biomechanics of screw fixation through joint was better than wire technique and Halifax. The screw fixation avoids occipitocervical fusion, and has a high requirement to instal ation. When an internal fixator was selected, immediate cervical vertebra stability should be provided to protect spinal cord functions. Upper neck functions should be maintained to reach reduction and maintenance of occipital bone, atlas and axis. A suitable fixation method should be selected for each patient.%背景：随着对寰枢椎结构形态学、应用解剖学和生物力学的研究日趋深入，寰枢椎不稳的发生机制以及诊治越来越受到关注。但对寰枢椎不稳定性疾病的有效内固定治疗开展相对较晚，为此国内、外的学者进行了大量的研究。 目的：比较寰枢椎后路内固定修复中几种不同内固定方式的生物力学性能，评价其各自的稳定性。 方法：通过检索近年来关于不同后路内固定方式修复寰枢椎不稳定的对比性生物力学评价及其初步临床应用研究的相关文献，通过对正常人体的寰枢椎复合体、寰枢椎不稳模型的三维运动范围的测量等相关研究成果作回顾性分析，评价不同内固定方案在正常枕寰枢三维运动下的稳定性，为临床合理选择内固定提供生物力学基础。 结果与结论：寰枢椎后路固定包括Gal ie钢丝固定、Brooks固定、Apofix和Halifax固定椎板钩内固定、经关节螺钉内固定以及寰枢椎椎弓根钉棒系统内固定等。Gal ie 技术有利于前方半脱位的复位，但力学稳定性较差。Brooks技术有很强的旋转和牵张力。Apofix和Halifix椎板钩装置提供更强的抗旋转与抗前移强度，力学上较Gal ie技术稳定，经关节螺钉固定生物力学优于钢丝技术和Halifax，避免了枕颈融合固定，对于安装技术有较高要求。在选择内固定时,既要注意应能提供即刻的颈椎稳定，以保护脊髓功能，又要尽可能保留上颈段的功能，达到枕骨、寰椎、枢椎间的解剖复位和维持，应根据每例患者的具体情况，选择合适的内固定方法。
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