后路经寰枕关节-斜坡螺钉枕颈固定技术的可行性研究

目的探讨经寰枕关节-斜坡螺钉行后路枕颈固定的解剖学可行性。方法回顾性分析2017年2月至2019年11月60例来院就诊并行枕颈区CT检查的成人CT影像资料,排除枕颈区域感染、损伤、肿瘤和畸形。利用CT扫描的Dicom数据在Mimics软件中进行解剖学参数测量,测量参数包括斜坡前缘、中部的高度和宽度,斜坡前方软组织最薄处厚度,枕骨髁关节面前后径、横径及内倾角,舌下神经管最低点至枕骨髁关节面垂直距离,上关节面前后径和横径,侧块高度,寰椎下关节突高度和宽度;再行三维数字化建模并模拟置入直径为3.5 mm的螺钉,在3-Matic软件中测量置钉参数,包括螺钉内倾角、头倾角及长度。取8具尸体标本,后方暴露颅颈交界区,按上述置钉参数将直径为3.5 mm的钛合金螺钉自寰椎下关节突与后弓移行处置入,经寰枕关节至斜坡;然后用摆锯沿钉道剖开,观察螺钉的钉道轨迹,验证置钉的安全性和有效性。结果男性斜坡前缘高度和宽度分别为(16.8±2.5)mm和(20.1±3.1)mm;斜坡中部分别为(9.7±2.3)mm和(22.4±3.7)mm。斜坡前方软组织最薄处厚度为(5.8±1.48)mm。枕骨髁前后径为(19.1±1.9)mm,横径(12.6±2.0)mm,内倾角为33.7°±4.5°。舌下神经管最低点至枕骨髁关节面垂直距离为(9.6±1.1)mm。寰椎侧块高度为(12.9±2.4)mm。上关节面前后径为(21.7±1.9)mm,横径为(11.7±1.4)mm。寰椎下关节突宽度为(14.9±1.4)mm,高度为(5.7±0.85)mm。螺钉进钉点至侧块移行中点所在垂线的距离为(2.5±0.6)mm,至中点所在水平线的距离为(2.3±0.7)mm;内倾角为18.4°±1.6°,调整范围为15.0°±2.8°;头倾角为55.6°±3.1°,调整范围为10.4°±2.4°;钉道长度为(53.0±2.8)mm。女性的解剖学参数较男性略小,差异有统计学意义,左右侧参数比较差异无统计学意义。8具标本的经寰枕关节-斜坡螺钉均能安全、有效置入。结论经寰枕关节-斜坡螺钉可在不损伤神经、血管结构的情况下安全置入,可以作为枕颈固定方式的一种选择。

Anatomic study of posterior atlanto-occipital-clivus screw technique

Objective To investigate the anatomical safety and feasibility ofposterior occipitocervical fixation with atlan-tooccipital-clivus screw.Methods Data of 60 patients who treated in the spinal department of our hospital with upper cervical computed tomographic scans from February 2017 to November 2019 were retrospectively collected.Occipitocervical infection,injury,tumor and deformity were excluded.The Mimics software was used to reconstruct the occiput,atlas and measure the anatomical parameters,including the height and width of the anterior edge of the clivus,the height and width of the middle part of the clivus,the thinnest distance of the soft tissue in front of the clivus,the anteroposterior diameter,transverse diameter,the angle of inside tilting in coronary plane of the occipital condyle,the distance from the hypoglossal canal to the atlantooccipital articular surface,the anteroposterior diameter and transverse diameter of the superior joint of atlas,the height of the lateral mass,and the height and transverse diameter of the inferior articular process of the superior atlas joint.The three-dimensional digital modeling was performed and the screw diameter of 3.5mm was simulated.3-Matic software were used to measure the screw placement parameters,including the inside tilting angle in coronary plane of screw,and the angle of upper tilting in sagittal plane and length of screw.The atlanto-occipital junction was exposed at the rear of 8 cadavers.According to the above parameters,the titanium alloy screws with a diameter of 3.5 mm were transferred from the inferior articular process and posterior arch of the atlas to the clivus through the atlantooccipital.Finally,the screw path was cut along the nail path with a pendulum saw,and the track of the screw was observed to confirm the safety and effectiveness of the screw.Results The leading edge height and width of male clivus was 16.8±2.5 mm and 20.1±3.1 mm.The middle part of the clivus was 9.7±2.3 mm and 22.4±3.7 mm.The thinnest soft tissue in front of the clivus was 5.8±1.48 mm.The anteroposterior diameter of the occipital condyle was 19.1±1.9 mm,the transverse diameter was 12.6±2.0 mm,the inside tilting angle was 33.7°±4.5°,and the vertical distance from the lowest point of the neural tube to the articular surface of the occipital condyle was 9.6±1.1 mm.The height of the lateral mass of atlas was 12.9±2.4 mm,the anteroposterior diameter of the upper joint of atlas was 21.7±1.9 mm,and the transverse diameter was 11.7±1.4 mm.The width of the inferior facet was 14.9±1.4 mm and the height of the inferior facet was 5.7±0.85 mm.The distance from the screw entry point to the vertical line of the lateral mass migration midpoint was 2.5±0.6 mm;The distance from the screw entry point to the horizontal line of the midpoint was 2.3±0.7 mm.The inside titling angle of screw was 18.4°±1.6°,the upper tilting angle was 55.6°±3.1°,the length of the screw track was 53.0±2.8 mm,the adjustment range of upper tilting angle was 15.0±2.8 mm,the adjustment range of inside tilting angle was 10.4±2.4 mm.The anatomical parameters of females were slightly smaller than those of males,and the difference was statistically significant,but there was no significant difference between left and right parameters.The screws of 8 specimens could be inserted safely and effectively.Conclusion Atlan-tooccipital-clivus screw can be implanted without damaging the nerve and vascular structure,and it can be used as a choice for occipitocervical fixation.