第2骶椎骶髂螺钉最佳进钉通道的分析

目的　利用数字化仿真技术确定并测量第二骶椎骶髂螺钉最佳进钉通道参数。 方法　将2011年4月至2011年7月入院的8例无骨盆病变患者（男性4例，女性4例，年龄25~53岁）的CT数据集导入Mimics10.01进行三维重建，利用数字化仿真技术生成骶椎阴模，利用透视骶椎阴模确定S2骶髂螺钉最佳进钉通道，利用空间解析几何测量相关参数。 结果　8例共16侧资料的S2骶髂螺钉最佳进钉通道均能以此方法确定。最佳进钉通道参数：最大半径男性为（6.38±0.54）mm，女性为（4.9±0.74）mm；深度男性为（68.93±3.49）mm，女性为（58.43±8.16）mm；与矢状面夹角男性为（73.48±8.57）°，女性为（79.93±　5.29）°；与横截面夹角男性为（14.07±6.22）°，女性为（6.95±4.81）°；与冠状面夹角男性为（7.12±7.11）°，女性为（5.87±5.01）°。最佳进钉点及最佳进钉终点的确定方法为：在骨盆出口位X线透视图像上，作一边长分别水平及垂直并恰好包围骨盆的矩形，以左下角顶点为原点，左上角顶点为（0,1），右下角顶点为（1,0）建立二维直角坐标系，进钉点坐标男性为（0.5±0.26，0.52±0.04），女性为（0.49±0.24，0.47±0.10）；进钉终点坐标男性为（0.5±0.01，0.59±0.07），女性为（0.5±0.02，0.49±0.14）。在骨盆入口位X线透视图像上，用相同的方法作一矩形并定义坐标系，进钉点坐标男性为（0.5±0.26，0.52±0.04），女性为（0.49±0.24，0.47±0.10），进钉终点坐标男性为（0.5±0.01，0.78±0.01），女性为（0.5±0.02，0.81±0.03）。S2骶髂螺钉最佳进钉通道参数男女对比“最大半径”、“深度”、“与横截面夹角”、“进钉点前后相对位置”有统计学差异（P<0.05），余无统计学差异。 结论　数字化仿真技术能精确确定S2骶髂螺钉最佳进钉通道参数。

The analysis of the optimum sacroiliac screw channel of the second sacral vertebra

Objective　Using Digital Simulation Technique(DST) to find and measure the optimum sacroiliac screw channel(OSSC) of the second sacral vertebra.　Methods　This study included 8 adult patients without pelvic disease admitted to the hospital In April 2011 to July 2011, and imports their pelvic CT scan data into Mimics for 3D reconstruction, and uses DST to establish the sacral cavity die, and uses the perspective of the sacral cavity die to determine the OSSC, and uses Space Analytical Geometry's (SAG) to measure it's parameters.　Results　All of the 8 cases (16 sides) can use DST to determine the OSSC of S2. The parameter of the OSSC of S2: The max radius is (6.38±0.54)mm in male, and(4.9±0.74)mm in female; The depth is (68.93±3.49)mm in male, and(58.43±8.16)mm in female; The angle with sagittal plane is (73.48±8.57)° in male, and(79.93±5.29)° in female; The angle with axial plane is (14.07±6.22)° in male, and(6.95±4.81)° in female; The angle with coronal plane is (7.12±7.11)° in male, and(5.87±5.01)° in female. The way to determine the initial point and the end point of OSSC: Draw a rectangle whose sides are horizontal or vertical to just right encircle the pelvic on the out-let pelvic X-ray films. Establish a 2-D rectangular coordinates whose origin is the lower left vertices of the rectangle, and point (0, 1) is the upper left vertices of the rectangle, and the point (1,0) is the lower right vertices of the rectangle. The coordinate of the initial point of OSSC is (0.5±0.26, 0.52±0.04) in male, and (0.49±0.24, 0.47±0.10) in female. The coordinate of the end point of OSSC is (0.5±0.01, 0.59±0.07) in male, (0.5±0.02, 0.49±0.14) in female. Use the same way to draw the rectangle and define the rectangular coordinates on the in-let pelvic X-ray films. The coordinate of the initial point of OSSC is (0.5±0.26, 0.52±0.04) in male, and (0.49±0.24, 0.47±0.10) in female. The coordinate of the end point of OSSC is (0.5±0.01, 0.78±0.01) in male, (0.5±0.02, 0.81±0.03) in female. Comparing between men and women, some parameters (the max radius, the depth, the angle with axial plane) have statistically significant difference(P<0.05),and the other have no statistically significant difference (P>0.05).　Conclusions　The DST can accurately determine the OSSC of S2.