寰椎椎弓根进钉通道的数字解剖学研究

Digital anatomic study of atlas pedicle screw channel

目的：探讨寰椎椎弓根进钉通道在矢状面角（SSA）为0°时不同水平面角（TSA）方向投影的变化规律。方法：将20例健康成年志愿者（男12例,女8例;年龄24~68岁,平均45岁）的寰椎CT连续断层扫描数据导入Mimics 10.01软件,三维重建寰椎数字解剖模型,将重建的结果以.stl格式保存,再将寰椎数字模型导入UG Imageware 12.0,建立寰椎椎弓根进钉通道数字化分析方法,确定三维参考平面,分析在SSA为0°时左右椎弓根TSA分别从0°～30°,均匀间隔5°,观察280个寰椎椎弓根进钉通道的长度和内切圆半径的变化规律。结果：280个寰椎椎弓根进钉通道的长度为20.54～33.21mm,其中11个通道长度小于最短椎弓根螺钉长度（〈22mm）;TSA为0°进钉时左右通道长度均最大,左右侧比较无显著性差异（P〉0.05）,5°～30°进钉时同一进钉角度左右侧比较有显著性差异（P〈0.05）;同侧不同进钉角度比较无显著性差异（P〉0.05）。280个寰椎椎弓根螺钉通道的内切圆半径为1.38～2.51mm,其中有42个内切圆半径小于最小椎弓根螺钉半径（〈1.75mm）;同一进钉角度右侧内切圆半径与左侧比较及同侧不同进钉角度比较均无显著性差异（P〉0.05）。结论：不同个体甚至同一个体的左右两侧椎弓根形态之间有较大差异。部分寰椎椎弓根进钉通道长度和内切圆半径小于椎弓根螺钉最小长度和最小半径,椎弓根进钉通道内切圆半径小于最小椎弓根螺钉半径时置钉会穿破椎弓根的皮质骨,不适合采用经寰椎椎弓根螺钉内固定技术。术前用数字化技术测量寰椎椎弓根进钉通道可以实现个体化置钉。

Objective：To investigate the regular pattern of atlas pedicle screw channels in different transverse section angles（TSA） when placed as 0° sagital section angles（SSA）.Method：CT scan images of atlas of 20 healthy adult volunteers （12 males,8 females;aged 24-68,average 45 years old） were digitally analyzed by Mimics 10.01 software （Materialise）,and their three-dimensional （3D） models were established.These models were saved as .stl format,then imported to UG Imageware 12.0 software to establish the digital method for an- alyzing the atlas pedicle screw channels,and determine the reference 3D plane,under the condition of SSA at 0° invariably,TSA changed evenly between 0°-30° at an interval of 5°.The changing pattern of the length and the inscribed circle radius of 280 atlas pedicle screw channels were analyzed.Result：The length of the 280 atlas pedicle screw channels was about 20.54-33.21mm.11 channels were shorter than the shortest screw length （22mm）.The changing pattern of the length of atlas pedicle screw channels was that when the trans- verse section angles of the entering screw was 0°,the length was the longest.No side-related difference was noted（P0.05）.When the angle was between 5°-30°,the side-related difference was significant（P0.05）.Ipsilat- eral varied angle of the entering screw showed no significant difference（P0.05）.The inscribed circle radius of 280 atlas pedicle screw channels was between 1.38-2.51mm;42 inscribed circle radius were shorter than the shortest ones（1.75mm）.No side-related difference was significant（P0.05）;Ipsilateral varied angle of the en- tering screw showed no significant difference （P0.05）. Conclusion：The morphology of bilateral pedicle of C1 vary significantly in different patients,or even in the same patient.In some patients,the pedicle channelslength and the inscribed circle radius are less than the minimum length and radius of pedicle screw,which will predispose the pedicle at risk.Customized screw placement can be reached by preoperative digital measurement of atlas pedicle screw channels.