正中矢状面上S_2和S_1椎体前缘夹角对骨盆入口位的影响

Influence of the included angle between anterior aspects of S_2 and S_1 vertebral bodies on pelvic inlet imaging in mid-line sagittal plane

目的：探讨正中矢状面上S2、S1椎体前缘夹角对骨盆入口位的影响.方法：筛选出58例患者的骨盆轴向CT扫描图像作为研究对象,其中男43例,女15例;年龄18～68岁,平均40.7岁.于每一例骨盆CT的正中矢状面上分别测量S2、S1椎体前缘与水平面间夹角来模拟由骨盆正位进行骨盆入口位投照时所需要的最佳X线调整角度.以S2与水平面间夹角为基数并减去S1与水平面间夹角来计算两者间的差值,进而评判S2、S1椎体前缘夹角对骨盆入口位的影响.应用SPSS16.0统计软件对测量结果进行配对t检验,可信区间设为95％,差异的显著性设为P＜0.05.结果：S2椎体前缘与水平面间夹角平均（30.5±6.5）°,S1椎体前缘与水平面间夹角平均（25.7±5.9）°,两组角度间差异有统计学意义（t=3.35,P=0.001）.S2、S1椎体前缘夹角为零度者10例;负角14例,平均-（8.9±8.1）°;正角34例,平均（11.8±6.4）°.结论：正中矢状面上S2、S1椎体前缘夹角使得S1入口位在绝大多数情况下不同于S2入口位,且对S1、S2入口位的成像及应用的可靠性均有影响.根据术前骨盆CT正中矢状面的测量结果透视出患者个体化的S1、S2入口位可准确地指导相应S1、S2骶髂螺钉的置入操作.

Objective：To analyze the influence of included angle between the anterior aspects of S2 and S1 vertebral bodies on pelvic inlet imaging in the pelvic midline sagittal plane.Methods：Totally 58 axial pelvic CT scans were chosen as study objects including 43 males and 15 females,with an average age of 40.7 years old （ranged,18 to 68 years old）.The angles between the anterior aspects of S2 and S1 vertebral bodies and the horizontal plane on midline sagittal CT reconstruction were measured to simulate the optimal S2 and S1 inlet angles.The included angle between the anterior aspects of S2 and S1 vertebral bodies was calculated by subtrocting the S1,inlet angle from the S2 inlet angle defined as a base number.Then,the impact of the calculated included angles on the pelvic inlet imaging was analyzed.Results：The S2 inlet angles averaged （30.5±6.5） degrees;the S1 inlet angles averaged （25.7±5.9） degrees.The difference between them was significant （t=3.35,P=0.001）.Ten patients had zero angle between the anterior aspects of S2 and S1 vertebral bodies; 14 patients had negative angle,averaged（8.9±8.1） degrees ; 34 patients had positive angle,averaged （11.8±6.4） degrees.Conclusion：The difference of included angle between the anterior aspects of S2 and S1 vertebral bodies leads to the difference between S1 inlet view and S2 inlet view in most cases,complicating the pelvic inlet imaging,and affecting the reliability of the application of pelvic inlet view.Utilizing the angles measured on the preoperative midline sagittal CT reconstruction to obatin the patient-customized S1 and S2 inlet views could accurately guide the S1 and S2 iliosacral screw insertion.