Tannoury Tony, Saade Aziz, Thomas Dylan Chevalier, Wisco Jonathan, Ajmi Qasim, Singh Varun, AbdalKader Mohamad, Tannoury Chadi
Boston Medical Center, Boston, Massachusetts.
Boston University School of Medicine, Boston, Massachusetts.
JB JS Open Access. 2023 Sep 6;8(3). doi: 10.2106/JBJS.OA.22.00079. eCollection 2023 Jul-Sep.
Sacral (S1) pedicle screw misplacement in posterior percutaneous fixation (PPF) can be related to anatomical variability and a lack of reliable radiographic landmarks. This study highlights a reproducible anatomical landmark (the "V" sign) for the safe localization of the S1 pedicle entry point under fluoroscopy.
Human cadavers (n = 14) were dissected for the anatomical description of the "V" landmark and its relationship with the entry point of the S1 pedicle screw. The "V" landmark was defined medially by the lateral border of the superior articulating process of S1 and laterally by the posterior projection of the sacral ala. The mean distance was measured between the bottom point of the "V" landmark and the anatomical entry point to the S1 pedicle (V-S1 entry point distance). A similar measurement was conducted on computed tomography (CT) scans of 135 patients who underwent PPF using the "V" sign as a landmark for S1 pedicle screw placement (270 screws). These were retrospectively evaluated for appropriateness of S1 screw entry points and for proper S1 screw alignment and breaches.
In the 14 cadavers, irrespective of the laterality and sex, the V-S1 entry point distance averaged 11.7 mm. On the medial-lateral axis, all entry points converged within 2 mm of a vertical line intersecting the base of the "V." Additionally, the CT scan analysis (135 patients, 270 screws) revealed an optimal entry point for 100% of the screws and a 3.3% (n = 9 screws) breach rate. Six of the 9 identified breaches were minor, and only 1 (0.4% of the 270 screws) warranted revision.
The "V" sign serves as a reliable anatomical and radiographic landmark for identifying the S1 pedicle entry point under fluoroscopic guidance. This landmark can help surgeons overcome the radiographic ambiguity of the sacral anatomy and ultimately reduces the rate of S1 pedicle screw misplacement.
Diagnostic Level IV. See Instructions for Authors for a complete description of levels of evidence.
在经皮后路固定（PPF）中，骶骨（S1）椎弓根螺钉位置不当可能与解剖变异及缺乏可靠的影像学标志有关。本研究强调了一种可重复的解剖标志（“V”征），用于在荧光透视下安全定位S1椎弓根进针点。
对14具人体尸体进行解剖，以描述“V”标志及其与S1椎弓根螺钉进针点的关系。“V”标志内侧由S1上关节突的外侧缘界定，外侧由骶骨翼的后突界定。测量“V”标志的最低点与S1椎弓根解剖进针点之间的平均距离（V-S1进针点距离）。对135例行PPF并以“V”征作为S1椎弓根螺钉置入标志的患者的计算机断层扫描（CT）图像进行类似测量（共270枚螺钉）。回顾性评估S1螺钉进针点的合适性以及S1螺钉的正确对线和穿破情况。
在14具尸体中，无论左右侧别和性别，V-S1进针点距离平均为11.7mm。在内外侧轴线上，所有进针点都汇聚在与“V”底部相交的垂直线的2mm范围内。此外，CT扫描分析（135例患者，270枚螺钉）显示100%的螺钉进针点最佳，穿破率为3.3%（n = 9枚螺钉）。9枚已确认穿破的螺钉中有6枚为轻微穿破，仅1枚（占270枚螺钉的0.4%）需要翻修。
“V”征是在荧光透视引导下识别S1椎弓根进针点的可靠解剖学和影像学标志。该标志可帮助外科医生克服骶骨解剖结构在影像学上的模糊性，最终降低S1椎弓根螺钉位置不当的发生率。
诊断性研究IV级。有关证据水平的完整描述，请参阅《作者须知》。
