BACKGROUND:Atlantoaxial anatomical structures were special. Compared with thoracolumbar vertebrae, there is no fixed anatomical marker for screw implantation. Moreover, pedicle structural variation is great. The current consensus view is to suggest an individualized program of pedicle screws. The development of orthopedic digital software technology provides a novel manner for preoperative design. OBJECTIVE:To original y design 3D matrix model, to observe atlas pedicle channel, pedicle screw safety zone, to measure optimal program for screw fixation, and to simplify preoperative design of entering pedicle screw. METHODS:Continuous atlas CT data of 12 healthy adults in picture archiving and communication system of People’s Hospital, Three Gorges University were imported into Mimics 10.01 software. There were seven males and five females, at the age of 30-65 years old, averagely 45 years. After three-dimensional reconstruction, the three-dimensional reconstruction models were imported into 3Dmax 2009 as .dwg format. The reference three-dimensional planes and the sites of nail insertion were determined by the atlas modeling. The modeling consisted of 17×17×2 elements and the transverse section angles ranged from 0° to 40° and the sagittal section angles ranged from 0° to 40° with a space of 2.5°. 578 elements were used to simulate pedicle screw array model. Perspective observation showed that the diameter was 3.5 mm, and length was 22 mm in pedicle channel. Thus, safety area, best screw channel and screw angle were analyzed. RESULTS AND CONCLUSION:The total number of elements in the matrix study was 17×17×2×12 in 12 subjects. 175 screws in total of 6 936 units could safely meet the operative standard. No significant difference in the number of pedicle screw between left and right sides (P>0.05). Results indicated that the digital three-dimensional modeling technology is an effective, simple, accurate way in the preoperative design and measurement for atlas pedicle surgery.%背景：寰枢椎解剖结构特殊，同胸腰椎相比，置钉点缺乏固定的解剖标志，而且椎弓根结构变异较大，目前一致的观点是建议个体化的置钉方案。骨科数字软件技术的发展为术前设计提供了新的技术手段。 目的：原创设计出3D矩阵模型，观察寰椎椎弓根通道、置钉安全区，测量最佳置钉方案，简化寰椎椎弓根螺钉进钉方案的术前设计。 方法：将三峡大学人民医院影像归档和通信系统中12例健康成人的寰椎CT连续断层扫描数据导入Mimics 10.01软件，其中男7例，女5例；年龄30-65岁，平均45岁，三维重建后利用.dwg文件导入3dmax2009。确定三维参照坐标和进钉点，用3dmax中参考建模命令建立17×17×2，间距2.5°，水平面角0°-40°，矢状面角0°-40°，共578个元素模拟椎弓根螺钉阵列模型，通过透视图观察直径为3.5 mm，长度为22 mm模拟螺钉在椎弓根通道中的情况，从而确定安全区，测量最佳置钉方案及螺钉角度。 结果与结论：12例受试者矩阵研究元素总数目为17×17×2×12，共6936个元素单位。其中175个元素符合进钉要求，左、右侧椎弓根内螺钉数目比较，差异无显著性意义(P>0.05)。提示利用数字3D建模技术能有效、简单、精确的进行寰椎椎弓根置钉的术前设计。
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