Liawrungrueang Wongthawat, Riew K Daniel, Sugandhavesa Nantawit, Bunmaprasert Torphong
Department of Orthopaedics, School of Medicine, University of Phayao, Phayao, Thailand.
Department of Neurological Surgery, Weill-Cornell Medicine and Department of Orthopedic Surgery, The Och Spine Hospital at New York Presbyterian Hospital, Columbia University, New York, NY, USA.
Eur Spine J. 2022 Dec;31(12):3443-3451. doi: 10.1007/s00586-022-07385-7. Epub 2022 Sep 19.
To compare the Atlas (C1) lateral mass screw placement between screw trajectories of 0° and 15° medial angulation while using the intersection between lateral mass and inferomedial edge of the posterior arch.
Forty-eight Atlas lateral masses were prepared and divided into 2 groups: Group 1; screws inserted at 3 mm lateral to the reference point with screw trajectory of 0° angulation(N = 24) and Group 2; those inserted with screw trajectory of 15° medial angulation(N = 24). We evaluated the atlas anatomy, screw purchase and the presence of any breaches using CT scan.
The radiographic parameters for Groups 1 and 2 were found statistically different (p-value < 0.05): bilateral intraosseous screw lengths (17.92 ± 1.47 mm. vs. 20.71 ± 2.4 mm.), bilateral screw length (29.92 ± 1.72 mm. vs. 33.13 ± 1.78 mm.), left screw medial angulation (x°) (0.67° ± 0.78° vs.14.17° ± 3.51°), right screw medial angulation (y°) (0.83° ± 1.03° vs.14.25° ± 2.53°) and bilateral screw medial angulation (0.75° ± 0.9° vs. 14.21° ± 2.99°). Twenty-two screws (91.67%) using the 0° medial angulation and nineteen screws (79.17%) using the 15° medial angulation had no cortical violations (Grade 0). However, two screws (8.33%) with 0° medial angulation and five screws (20.83%) with 15° medial angulation had breach less than 2 mm (Grade 1). There were no screws with breach between 2 and 4 mm (Grade 2) or greater than 4 mm. (Grade 3).
A starting point of 3-mm lateral to the intersection between lateral mass and inferomedial edge of the Atlas posterior arch can be safely and effectively used to insert C1 lateral mass using both 0° and 15° medial angulation.
在使用寰椎侧块与后弓下内侧缘的交点时，比较0°和15°内侧成角的螺钉轨迹下寰椎（C1）侧块螺钉的置入情况。
准备48个寰椎侧块并分为2组：第1组，在参考点外侧3mm处插入螺钉，螺钉轨迹为0°成角（N = 24）；第2组，螺钉轨迹为15°内侧成角（N = 24）。我们使用CT扫描评估寰椎解剖结构、螺钉把持力以及是否存在任何骨皮质破损情况。
发现第1组和第2组的影像学参数存在统计学差异（p值<0.05）：双侧骨内螺钉长度（17.92±1.47mm对20.71±2.4mm）、双侧螺钉长度（29.92±1.72mm对33.13±1.78mm）、左侧螺钉内侧成角（x°）（0.67°±0.78°对14.17°±3.51°）、右侧螺钉内侧成角（y°）（0.83°±1.03°对14.25°±2.53°）以及双侧螺钉内侧成角（0.75°±0.9°对14.21°±2.99°）。使用0°内侧成角的22枚螺钉（91.67%）和使用15°内侧成角的19枚螺钉（79.17%）无骨皮质侵犯（0级）。然而，2枚（8.33%）0°内侧成角的螺钉和5枚（20.83%）15°内侧成角的螺钉骨皮质破损小于2mm（1级）。没有骨皮质破损在2至4mm之间（2级）或大于4mm（3级）的螺钉。
在寰椎后弓侧块与下内侧缘交点外侧3mm处作为起始点，可安全有效地用于0°和15°内侧成角的C1侧块螺钉置入。
