Department of Spine Surgery, Affiliated Hospital of Qingdao University Medical College, Qingdao, China.
Eur Spine J. 2010 May;19(5):828-32. doi: 10.1007/s00586-010-1331-z. Epub 2010 Feb 21.
This paper reports a morphometric study of the C2 laminae to provide quantitative anatomical data for safe crossing laminar screw placement. A valid trajectory is essential for C2 crossing laminar screw placement. Although several clinical technique notes and modifications to define a safe screw trajectory have been introduced in the recent years, no morphometric analysis has been performed to confirm the accuracy of screw trajectory using this technique. In this study, morphometric analysis was performed on 100 Korean C2 three-dimensional reconstruction CT images. The reconstructive C2 vertebrae from the post-edge of the spinal canal to the spinal process were divided into several zones, 1 mm each. Each zone was chosen as the entry point to imitate a crossing laminar screw (3.5 mm diameter) placement. In each 1-mm zoned trajectory, the screw pass ratio (PR), safe screw angle range (SAR) and maximum screw length (MSL) were measured and compared with the data from the other zoned trajectories. The zone '5-6 mm posterior to the post-edge of the spinal canal' was found to be a more feasible and safer entry point for guiding a crossing laminar screw placement than the other zones because this zone could provide a trajectory with maximal PR (85%), SAR (9.57 +/- 4.36 masculine) and a larger MSL (21.74 +/- 2.44 mm) than the other areas. The recommended safe screw angle in the axial plane is 49.68 +/- 4.94 to 59.19 +/- 4.70 masculine. However, the screw angle can vary considerably according to the individual variance. A preoperative evaluation of the screw trajectory is essential for safe screw placement using this technique.
本研究对 C2 椎板进行形态学测量，为安全的经椎板螺钉固定提供定量解剖学数据。有效的进钉轨道对于 C2 经椎板螺钉固定至关重要。尽管近年来已经提出了几种临床技术说明和改良方法来确定安全的螺钉轨道，但尚未进行形态学分析来验证使用该技术的螺钉轨道的准确性。本研究对 100 例韩国 C2 三维重建 CT 图像进行了形态学分析。将从椎管后缘到棘突的重建 C2 椎体分为若干区域，每个区域 1mm。每个区域都被选为模拟经椎板螺钉（3.5mm 直径）置入的进钉点。在每个 1mm 分区的轨道中，测量螺钉通过率（PR）、安全螺钉角度范围（SAR）和最大螺钉长度（MSL），并与其他分区轨迹的数据进行比较。结果发现，“椎管后缘后 5-6mm 区”是更可行和安全的进钉点，因为该区域可以提供最大 PR（85%）、SAR（9.57+/-4.36 度）和较大 MSL（21.74+/-2.44mm）的轨道，优于其他区域。在轴位，推荐的安全螺钉角度为 49.68+/-4.94 度至 59.19+/-4.70 度。然而，螺钉角度可能会因个体差异而有很大变化。使用该技术进行安全螺钉固定时，术前评估螺钉轨道至关重要。
