3D影像模型测量S1骶髂关节螺钉最佳通道及其临床应用

The optimal pathway for S1 sacroiliac screwing: 3D imaging study and clinical application

目的在3D影像模型上测量S1骶髂关节螺钉的最佳螺钉通道,并临床观察骶髂关节螺钉的置入过程。方法收集54例成年中国人的正常骨盆CT扫描数据,重建出右半骨盆的三维模型。透明化处理后旋转模型至S1椎弓根轴位像下,微调角度使卵圆形的半透明安全区面积达到最大。模拟在最大安全区中央置入1枚与其边界相切的最大螺钉,测量螺钉直径、长度、进钉点到坐骨大切迹水平切线和髂后上棘垂直切线的距离,以及出钉点到S1椎体上终板和前皮质的距离,比较性别之间的差异。回顾性分析2014年1月至2016年1月期间南方医科大学南方医院创伤骨科根据上述结果置入骶髂关节螺钉(共置入16枚)的12例骶髂关节骨折脱位患者资料,男8例,女4例;年龄16~47岁,平均34岁;骨折按Tile分型:Ⅱ型6例,Ⅲ型6例。观察患者螺钉的置入情况。结果在S1椎弓根轴位像,所有骨盆3D影像模型都能找到界限清楚的卵圆形半透明安全区。S1骶髂关节螺钉最佳通道的最大直径为(13.66±2.04)mm,长为(77.66±4.25)mm,进钉点到坐骨大切迹水平切线的距离为(32.77±4.55)mm,到髂后上棘垂直切线的距离为(49.57±5.24)mm;出钉点到S1椎体上终板的距离为(9.30±1.54)mm,到骶骨前皮质的距离为(15.85±2.12)mm。男、女性之间最大直径、进钉点到髂后上棘垂直切线的距离、出钉点到骶骨前皮质的距离比较差异均有统计学意义(P<0.05)。12例患者16枚骶髂关节螺钉均安全置入。结论在骨盆3D影像模型上能方便、快捷地找到并量化S1骶髂关节螺钉的最佳螺钉通道参数,通过临床应用,证实其可为临床安全置钉提供理论基础。

Objective To determine the optimal pathway for S1 sacroiliac screwing based on the largest safe zone in Chinese population using 3D imaging models and observe its clinical application in patients with sacroiliac joint fracture or dislocation. Methods Pelvic CT scans of 54 Chinese adults were obtained to create reconstruction 3D models of the right hemi-pelvis.After the models were transparentized and rotated to the axial view of the S1 pedicle,the angle was slightly adjusted to maximize the translucent safe zone.Next,simulative insertion into the center of this zone was conducted with one virtual screw,as large as possible and tangent to the boundary.Measured were the diameter and length of the screw,the vertical distances from the entry point to the horizontal tangent line of the greater sciatic notch and to the vertical tangent line of the posterior superior iliac spine,and from the exit point to the S1 superior endplate and to the anterior cortex.The differences between males and females were analyzed.The above parameters of the optimal pathway for S1 sacroiliac screwing were used in insertion of 16 screws in the 12 patients with sacroiliac joint fracture or dislocation from January 2014 to January 2016 at Department of Orthopaedics and Traumatology,Nanfang Hospital.They were 8 males and 4 females,from 16 to 47 years of age (average,34 years).According to the Tile classification,6 cases belonged to Type Ⅱ and 6 ones to Type Ⅲ.The efficacy of S1 sacroiliac screwing was observed. Results In all the pelvic 3D imaging models,an oval translucent area for safe screw insertion could be easily identified from the S1 pedicle axial view.The maximum diameter and length of the optimal intraosseous pathway were 13.66±2.04 mm and 77.66±4.25 mm;the vertical distances from the entry point to the horizontal tangent line of the greater sciatic notch and to the vertical tangent line of the posterior superior iliac spine were 32.77±4.55 mm and 49.57±5.24 mm;the vertical distances from the exit point to the S1 superior endplate and to the anterior cortex were 9.30±1.54 mm and 15.85±2.12 mm.The differences were of statistical significance between males and females regarding the maximum diameter,the distance from the entry point to the vertical axis,and the distance from the exit point to the anterior cortex (P<0.05).All the 16 screws were safely implanted in the 12 patients. Conclusion The optimal screw pathway can be easily identified and its parameters can be measured in pelvic 3D imaging models using computer virtual technology.The clinical application has proved that the parameters can serve as a theoretical basis for safe placement of S1 sacroiliac screws.