BACKGROUND Determining the proper iliosacral screw orientation in a dysmorphic S1 sacral segment using a C-arm is difficult, and pelvic computed tomography (CT) is often necessary for the preoperative planning. On the preoperative pelvic axial CT section, the intended screw trajectory can be delineated intraosseously along the axis of the oblique osseous corridor. An inherently accurate orientation would be determined by 2 factors: (1) the trajectory is in the pelvic transverse plane, and (2) it is oriented relative to the coronal plane at a patient-specific angle, which should be measured preoperatively. Based on the above reasoning, we aimed to simplify and verify the orientation. METHODS After establishing the starting point on the sacral lateral view, we tested a method of simplifying the guidewire orientation: placing the guidewire in the pelvic transverse plane and then manipulating it to be angled relative to the coronal plane at the preoperatively measured patient-specific angle. The guidewire orientation should then be reproducibly accurate on the pelvic outlet and inlet views. The feasibility and safety of our method were verified through computer-simulated virtual surgical procedures in 95 dysmorphic sacra and clinical surgical procedures in 12 patients. The primary outcome parameters were the guidewire orientation and screw placement accuracy. RESULTS Using our method, the S1 guidewire orientation was reproducibly accurate on the pelvic outlet and inlet views in all of the virtual and clinical surgical procedures. Ninety-five virtual S1 screws (1 screw in each left hemipelvis) were placed intraosseously in the pelvic transverse plane. Fourteen unilateral S1 screws were placed intraosseously in the pelvic transverse plane in the 12 patients (2 patients had double screws) without iatrogenic injuries. CONCLUSIONS The guidewire orientation can be simplified by placing the guidewire in the pelvic transverse plane and replicating the preoperatively measured patient-specific angle between the guidewire and the coronal plane. After establishing the starting point on the sacral lateral view, our simplified manipulation yields a reproducibly accurate orientation on the pelvic outlet and inlet views. LEVEL OF EVIDENCE Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

中文翻译：

---

简化 S1 髂骶螺钉放置在畸形骶骨中的方向。


背景 使用 C 形臂确定畸形 S1 骶骨段中正确的髂骶螺钉方向很困难，并且骨盆计算机断层扫描 (CT) 通常是术前计划所必需的。在术前骨盆轴向 CT 切片上，可以沿着斜骨通道的轴线在骨内勾画出预期的螺钉轨迹。本质上准确的定向将由两个因素决定：(1) 轨迹位于骨盆横切面上，(2) 它相对于冠状面以患者特定的角度定向，该角度应在术前测量。基于以上推理，我们旨在简化和验证方向。方法 在骶骨侧视图上建立起点后，我们测试了一种简化导丝定向的方法：将导丝放置在骨盆横切面中，然后按照术前测量的患者特定角度操纵它相对于冠状面成一定角度。 。然后，导丝方向应在骨盆出口和入口视图上重复准确。通过计算机模拟的95例骶骨畸形虚拟手术和12例患者的临床手术验证了该方法的可行性和安全性。主要结果参数是导丝方向和螺钉放置精度。结果使用我们的方法，在所有虚拟和临床手术过程中，S1 导丝方向在骨盆出口和入口视图上都具有可重复的准确性。 95 个虚拟 S1 螺钉（每个左半骨盆各 1 个螺钉）骨内放置在骨盆横切面上。 12 名患者（2 名患者使用双螺钉）骨盆横切面骨内放置 14 颗单侧 S1 螺钉，无医源性损伤。结论 通过将导丝放置在骨盆横切面上并复制术前测量的导丝与冠状面之间的患者特定角度，可以简化导丝定向。在骶骨侧面视图上建立起点后，我们的简化操作可在骨盆出口和入口视图上产生可重复的准确方向。证据级别 治疗级别 III。有关证据级别的完整描述，请参阅作者须知。