枢椎椎弓根峡部复合体三维形态学特征及其临床意义

Three-dimensional morphological characteristics and clinical significance of the pedicle-isthmus complex of axis

中文关键词:  枢椎  椎弓根-峡部复合体  三维结构  形态特征  Mimics软件

英文关键词:Axis  Pedicle-isthmus complex  Three-dimensional structure  Morphological characteristics  Mimics software

中文摘要:

  【摘要】 目的：测量正常枢椎椎弓根峡部复合体（pedicle isthmus complex，PIC）解剖形态学参数，分析PIC三维结构特征并讨论其临床意义。方法：收集西南医科大学附属医院2022年1月～2022年12月收治的颈椎或颈部CTA检查的100例无椎动脉高跨患者[男性57例，女性43例；年龄56.1±1.8岁（18～79岁）]和后路枢椎椎弓根螺钉固定且术后复查颈椎CT的28例患者[男性15例，女性13例；年龄55.5±14.6岁（18～80岁）]的影像资料。将原始CT数据上传至Mimics 21.0 软件，利用软件从枢椎上分割出双侧PIC，通过多平面重建技术（multiplanar reconstruction，MPR）重建坐标轴，在新坐标轴上对PIC复合体的上、中、下行断层切割，并确定PIC最前端、最狭部和最后端。在三维图像上测量PIC上、中、下断层最前端宽度、最狭部宽度、最后端宽度以及内倾角度。基于后路枢椎椎弓根置钉患者的螺钉是否穿破PIC分为穿破组及未穿破组。并以枢椎椎弓根螺钉为参照，测量螺钉中心点距离PIC上壁高度、PIC内壁宽度以及螺钉内倾角。结果：100例患者PIC各参数左右侧比较均无统计学差异，合并统计。男性在各分割层面PIC宽度均大于女性，差异有统计学意义（P<0.05）。冠状位视角PIC宽度结果显示：上层整体宽度为9.6±1.3mm，中层整体宽度为9.5±1.4mm，下层整体宽度为8.0±1.1mm，上层、中层整体宽度无统计学差异（P=0.41），其余各层之间差异有统计学意义（P<0.05）。横断位视角PIC整体宽度结果显示：最前端整体宽度为8.8±1.4mm，最狭部整体宽度为7.2±1.3mm，最后端整体宽度为11.0±1.5mm，各层之间差异有统计学意义（P<0.05）。PIC内倾角结果显示：上层内倾角为15.1°±8.7°，中层内倾角为19.5°±8.4°，下层内倾角为26.3°±9.0°，各层之间差异有统计学意义（P<0.05）。28例后路枢椎椎弓根螺钉内固定患者，共计50枚螺钉置入，未穿破组和穿破组各有25枚。未穿破组螺钉中心点距离PIC上壁高度[4.4（3.6～5.3）mm]和距离PIC内壁宽度[3.3（2.8～3.8）mm]小于穿破组[5.1（4.5～6.0）mm和4.0（3.1～5.4）mm，P<0.05]。两组之间螺钉内倾角无统计学差异[17.6°（10.5°～21.5°） vs 16.9°（9.6°～23.1°），P=0.854]。结论：不伴椎动脉高跨的正常PIC冠状位视角呈上宽下窄的形态特点，横断位视角呈前后宽、中间窄的形态特点，内倾角从上至下逐渐增大，提示该PIC三维结构呈现扭曲改变。将枢椎椎弓根-峡部作为复合体分析有助于更好地认识其解剖形态和变化特点，指导枢椎安全置钉的策略选择。

英文摘要:

  【Abstract】 Objectives: To analyze the 3D structural characteristics and discuss the clinical significance of pedicle-isthmus complex(PIC) through measuring the anatomical and morphological parameters of normal axis PIC. Methods: The imaging data of 100 patients without high-riding vertebral artery[57 males, 43 females, 56.1±1.8(18-79) years] undergone CT angiography(CTA) examinations of the cervical spine or neck and admitted to the Affiliated Hospital of Southwest Medical University between January 2022 and December 2022, and another 28 patients[15 males, 13 females, 55.5±14.6(18-80) years] undergone posterior C2 pedicle screw fixation and examined with CT scan of the cervical spine during the same period were collected. The original CT data were uploaded to Mimics 21.0 software, and bilateral PICs were segmented from the axis to construct a new coordinate axes with multiplanar reconstruction(MPR) technology. The upper, middle and lower faults of the PIC were cut on the new axes, and the front-most, narrowest and back-most parts of the PIC were determined. The widths of the front-most, narrowest and, back-most parts and inclination angles of the upper, middle and lower faults of PIC were measured on 3D images. Based on whether the PIC was punctured or not, the patients implanted with posterior C2 pedicle screws were divided into punctured group and non-punctured group. Using the axis pedicle screw as reference, the image parameters of screw position were measured, including the height from the screw midpoint to the PIC upper wall, the width of the screw midpoint to the PIC inner wall, and the screw inclination angle. Results: There was no statistical difference between the left and right side of PIC parameters in 100 patients. The width of PIC in males was greater than that in females at all levels, and the difference was statistically significant(P<0.05). The results of PIC width from a coronal perspective showed that the overall width of the upper layer was 9.6±1.3mm, the overall width of the middle layer was 9.5±1.4mm, and the overall width of the lower layer was 8.0±1.1mm. There was no statistical difference between the overall width of the upper layer and the middle layer(P=0.41), while the difference between the other layers was statistically significant(P<0.05). The overall width of the PIC from the cross-sectional perspective showed that the overall width of the front-most part was 8.8±1.4mm, the overall width of the narrowest part was 7.2±1.3mm, and the overall width of the back-most part was 11.0±1.5mm, with statistical significance among all layers(P<0.05). The results of PIC inclination showed that the upper layer inclination was 15.1°±8.7°, the middle layer inclination was 19.5°±8.4°, and the lower layer inclination was 26.3°±9.0°, and the differences among all layers were statistically significant(P<0.05). In the 28 patients fixed with posterior C2 pedicle screw, a total of 50 screws were inserted, with 25 screws each in the punctured group and non-punctured group. The distances from the screw midpoint to PIC upper wall [4.4(3.6-5.3)mm] and PIC inner wall [3.3(2.8-3.8)mm] in the non-punctured group was smaller than those in the punctured group[5.1(4.5-6.0)mm and 4.0(3.1-5.4)mm, P<0.05]. No statistical differences was found between the two groups in the screw inclination angles[17.6°(10.5°-21.5°) vs 16.9°(9.6°-23.1°), P=0.854]. Conclusions: The normal PIC without high riding vertebral artery is wide at top and narrow at bottom in the coronal view, and wide at front and back and thin in the middle in the transverse view. The gradual increase of the internal inclination angle from top to bottom indicates that the 3D structure of PIC is distorted. Analyzing the axis PIC as a whole is helpful to better understand its anatomical morphology and change characteristics, and to guide the selection of safe strategies in implanting axial pedicle screws.