Butt Bilal B, Gagnet Paul, Piche Joshua, Patel Rakesh, Park Paul, Aleem Ilyas S
Department of Orthopaedic Surgery, University of Michigan, Ann Arbor, MI, USA.
J Spine Surg. 2021 Sep;7(3):335-343. doi: 10.21037/jss-20-566.
Numerous techniques of C1 lateral mass screw placement have been described. We sought to delineate the radiographic angle of safety medially and laterally and describe a novel surgical technique of C1 lateral mass screw placement. We sought to (I) determine the angle of safety medially and laterally of the C1 lateral mass; (II) assess the size available of the lateral mass in the AP and coronal planes; (III) describe novel technique of insertion of a C1 lateral mass screw utilizing navigation and a novel start point.
We retrospectively reviewed cervical computed tomography (CT) images of normal adults. Radiographic measurements were then obtained using these images including the angle (degrees) of safety medially and lateral of the C1 lateral mass bilaterally, as well as the length and width (mm) of the C1 lateral masses. A novel surgical technique was used by identifying the confluence of the medial aspect of the posterior arch and the lateral mass. This confluence is then marked out as the C1 screw start point. Under navigation guidance, lateral mass screws were placed with 0 degrees of medial-lateral angulation from posterior to anterior.
Forty-five patients with a mean age of 52.6±25.6 years (33% female) were included. The mean medial and lateral angle of safety of the C1 lateral mass bilaterally was 23±3.8 degrees and 32±5 degrees, respectively. Average length and width of the lateral mass was 17.7 and 13.3 mm respectively.
This study describes the radiographic window of safety medially and laterally for safe and reproducible placement of C1 lateral mass screws. Further, a novel technique using a medial start point and navigation guidance with 0 degrees of angulation in the coronal plane is described. Further research is required to assess outcomes of patients utilizing this method as well as biomechanical studies to assess this construct strength compared to others that are frequently used.
已有多种C1侧块螺钉置入技术被描述。我们试图确定C1侧块内侧和外侧的影像学安全角度，并描述一种新型的C1侧块螺钉置入手术技术。我们试图：（I）确定C1侧块内侧和外侧的安全角度；（II）评估侧块在前后位和冠状位平面上的可用尺寸；（III）描述利用导航和一个新的起始点置入C1侧块螺钉的新技术。
我们回顾性分析了正常成年人的颈椎计算机断层扫描（CT）图像。然后使用这些图像进行影像学测量，包括双侧C1侧块内侧和外侧的安全角度（度），以及C1侧块的长度和宽度（毫米）。通过确定后弓内侧与侧块的汇合处，采用一种新型手术技术。然后将该汇合处标记为C1螺钉起始点。在导航引导下，从后向前以0度的内外侧角度置入侧块螺钉。
纳入45例患者，平均年龄52.6±25.6岁（33%为女性）。双侧C1侧块的平均内侧和外侧安全角度分别为23±3.8度和32±5度。侧块的平均长度和宽度分别为17.7毫米和13.3毫米。
本研究描述了C1侧块螺钉安全且可重复置入的内侧和外侧影像学安全窗口。此外，还描述了一种使用内侧起始点和冠状面0度角度导航引导的新技术。需要进一步研究以评估采用该方法的患者的预后，以及进行生物力学研究以评估该结构与其他常用结构相比的强度。
