目的　比较镁合金及钛合金Jefferson 骨折复位钢板（Jefferson-fracture reduction plate, JeRP）内固定系统对于不稳定型Jefferson骨折的固定效果和应力分布。  方法　通过CT扫描获取寰椎的空间结构信息，运用Solidworks软件建立JeRP内固定系统固定寰椎前弓双骨折三维实体模型，利用　Ansys软件模拟寰椎生理载荷中立位、屈伸、侧弯及旋转运动状态进行有限元分析，比较镁合金及钛合金　JeRP系统内固定后的应力分布，计算骨折端的移位和内固定材料的形变量分析内固定效果。  结果　（1）所建JeRP内固定系统固定寰椎前弓双骨折的三维有限元模型几何相似性好，应力分布合理。（2）JeRP系统内固定术后，在所有运动状态下，内固定系统主要应力均集中在JeRP钢板的中部及螺钉根部。屈伸运动时螺钉尖部以及侧弯运动时同侧螺钉中部亦承受较大应力。（3）生理载荷下，两种材料JeRP系统的钢板及螺钉最大应力均小于材料的屈服强度，内固定材料的形变量及骨折端的位移均非常小，骨折端均存在一定应力，但镁合金组大于钛合金组。  结论　两种材料JeRP内固定系统固定寰椎前弓双骨折时均具有足够的力学强度及良好的内固定效果，但理论上镁合金组在促进骨折愈合方面优于钛合金组。

Objective　To compare the stability and stress distribution of titanium alloy and magnesium alloy Jefferson-fracture reduction plate(JeRP) system for fixation of unstable Jefferson fracture.　Methods　The spatial structure information of atlas was obtained through CT scanning, and the geometry model of JeRP system for t fixation of unstable Jefferson fracture was established in Solidworks system. The internal structure changes, and the stress distribution of titanium alloy and magnesium alloy JeRP system and atlas were imitated and analyzed in Ansys13.0 system under physiological load in neutral, anteflexion, extension, lateral bending and rotation positions.　Results　(1) There were high geometric similarity and qualified stress distribution on the finite element model of JeRP system for fixation of unstable Jefferson fracture. (2) In different positions under physiological load, the stress of JeRP system was located mainly at the mid-part of the JeRP, the root and top of screws in anteflexion and extension position and, at the mid-part of screws in lateral bending position. (3) The maximum stress of JeRP system was less than the yield strength of titanium alloy and magnesium alloy under physiological load. The elastic strain of JeRP system and deformation of fracture were quite small. The fracture surface stress of magnesium alloy group was larger than the titanium alloy group.　Conclusion　Both the titanium alloy and magnesium alloy JeRP system have enough strength and effect of fixation for the treatment of unstable Jefferson fracture in physiological load, but magnesium alloy JeRP system is better than titanium alloy JeRP system in promoting fracture healing.