胸椎三皮质螺钉斜向固定的影像学研究

Imaging study of tri-cortical screw oblique fixation in thoracic spine

目的:通过模拟成人胸椎斜向置入三皮质螺钉,探究该钉道的影像学参数及其可行性和安全性。方法:回顾性分析2019年1月~2021年10月于我院行胸椎CT平扫的成人影像学资料。选取无胸椎解剖学异常者100例,其中男性50例,女性50例,年龄25~68岁,平均40.0±11.6岁。在LightSpeed影像学工作站上模拟胸椎三皮质螺钉的斜向固定钉道(T2~T12):以椎弓根下1/3连线与上关节突外侧缘连线的交点为三皮质螺钉的进钉点,对其三维图像进行重建,以其为中心进行旋转切割,以得到最长与最宽的理想钉道。测量钉道的尾倾角、内聚角、钉道的长度。不同性别三皮质螺钉钉道参数之间比较采用独立样本t检验验证其是否存在差异,不同椎体参数运用单因素方差分析检验。结果:三皮质螺钉斜向固定钉道的长度从T2~T12依次增大,且每个椎体层面上男性钉道长度明显长于女性(P<0.05)。钉道最短为T2,在该节段上男性钉道平均值最长为48.8±3.1mm,最短为40.2±1.8mm;女性钉道平均值最长为45.5±2.3mm,最短为37.4±1.7mm。钉道最长为T12,在该节段上男性钉道平均值最长为65.4±2.9mm,最短为54.5±2.1mm;女性钉道平均值最长为61.6±2.2mm,最短为51.4±1.6mm。置钉角度男女之间无统计学差异,各胸椎椎体之间存在一定统计学差异。尾倾角从T2~T6/T7逐渐减小,从T6/T7~T12逐渐增大。最大尾倾角及最小尾倾角的最大值位于T12层面,平均值分别为46.1°±2.2°和25.4°±1.5°;最大尾倾角及最小尾倾角的最小值位于T6层面,平均值分别为39.3°±2.5°和19.6°±2.1°。最适尾倾角最大值位于T2,平均值为44.2°±2.5°;最适尾倾角最小值位于T7,平均值为36.7°±2.4°。内聚角除去最小内聚角大致呈递减趋势,最大内聚角和最适内聚角均为从T2~T12呈先递减后递增的趋势。内聚角各项最大值均位于T2节段,最大内聚角平均值为38.5°±4.0°,最小内聚角平均值为22.6°±2.6°,最适内聚角平均值为30°±2.4°。最大内聚角最小值位于T7,平均值为25.2°±2.4°;最适内聚角最小值位于T8,平均值为19°±1.4°;最小内聚角位于T12,平均值为12.9°±2.3°。结论:本研究成功模拟出成人胸椎三皮质螺钉的斜向置入,证实了该技术的安全性和可行性,为该螺钉的临床应用提供了解剖学参数。

Objectives:To simulate tricortical screws oblique fixation in the thoracic vertebras of normal adults to determine the radiographic trajectory parameter and to evaluate its feasibility and safety.Methods:The imaging data of patients who underwent plain CT scan and three-dimensional reconstruction of thoracic spine in our hospital from January 2019 to October 2021 were analyzed retrospectively.100 patients without thoracic anatomical abnormalities were selected,including 50 males and 50 females,aged from 25 to 68 years old,with an average of 40.0±11.6 years.The trajectories of thoracic tricortical screws which were oblique fixed on the light speed imaging workstation were simulated:taking the intersection of the lower third connecting line of the pedicle and the connecting line of the lateral edge of the superior articular process as the entry point of the tricortical oblique screw,reconstructing its three-dimensional image,and taking it as the center for rotary cutting to obtain the longest and widest ideal screw path.The sagittal angle,transverse angle and length of the screw trajectories were measured.The normal distribution was verified between the same-sex parameters.The paired design t-test was used to verify the difference between the three cortical oblique screw channel parameters of different genders.One-way ANOVA was used to test for different vertebral parameters.Results:The length of screws′trajectories increased from top to bottom,and the length of males′trajectories were significantly longer than that of females at each vertebral level(P<0.05).The shortest average trajectories were in T2 level.On this segment,the longest average trajectory was 48.8±3.1mm for man,45.5±2.3mm for woman,the shortest average trajectory was 40.2±1.8mm for men and 37.4±1.7mm for women.The longest average trajectory was in T12.On this segment,the longest was 65.4±2.9mm and the shortest was 54.5±2.1mm for man,61.6±2.2mm and 51.4±1.6mm for woman.For screw placement angle,there was no statistical difference between genders,but there were certain statistical differences between thoracic vertebrae.The sagittal angle decreased from T2 to T6 or T7 and increased from T6 or T7 toT12.The maximum value of the maximum average sagittal angle and the minimum average sagittal angle were located at the T12 level,which were 46.1°±2.2°and 25.4°±1.5°respectively.The minimum values of the maximum and minimum average sagittal angles were located at T6,which were 39.3°±2.5°and 19.6°±2.1°respectively.The maximum value of the optimum average sagittal angle was located at T2,which was 44.2°±2.5°;The minimum value of the average optimum sagittal angle was located at T7,which was 36.7°±2.4°.Except for the minimum transverse angle,the maximum average transverse angle and the optimal average transverse angle decreased first and then increased from T2-T12.Each maximum value was located in T2 segment,with the maximum average transverse angle of 38.5°±4.0°,the minimum average transverse angle of 22.6°±2.6°,and the optimum average transverse angle of 30.0°±2.4°.The minimum value of the maximum average transverse angle was located at T7,which was 25.2°±2.4°;The minimum value of the optimum average transverse angle was located at T8,which was 19.0°±1.4°,and the minimum average transverse angle was located in T12,which was 12.9°±2.3°.Conclusions:This study successfully simulated the oblique fixation of adult tricortical screws in thoracic spine,which confirms the safety and feasibility of the screw,and also provides anatomical parameters for the clinical application of the screw.