成人退变性脊柱侧凸经骶2骶髂螺钉钉道轨迹的影像学研究

Imaging study of second sacral alar-iliac screw placement in adult degenerative scoliosis

目的探讨成人退变性脊柱侧凸畸形患者经第2骶椎骶髂螺钉(secondsacralalar-iliacscrew,S2AI螺钉)钉道轨迹的影像学特点。方法选取收治的40例退变性脊柱侧凸患者,男15例,女25例;年龄为51~81岁,平均(65±6.73)岁。应用螺旋CT行胸腰段、腰段、骶尾段脊柱、骨盆及双侧髋关节股骨侧近端扫描及三维重建。在重建图像中选取S1孔下缘与S2孔上缘间直线距离的中点、并外移至骶外侧嵴基底处作为进钉点;以进钉点至髂前下棘下缘作为S2AI螺钉置入的平面;以直径10 mm螺钉作为设计模板,以髂骨内皮质最低点为圆心做直径为5 mm的圆、选取进钉点至圆外径(髂骨内部分)相切的直线作为螺钉轨迹的轴心,并视为最佳钉道。横断位图像中测量钉道的外展角、钉道长度及髂骨宽度;矢状面图像中测量钉道尾倾角、钉道轴心距坐骨大切迹的距离、钉道轴心距髋臼上缘的距离。结果ADS患者S2AI螺钉钉道长度为(12.00±0.99)cm,外展角为41.24°±3.92°,尾倾角为27.73°±6.45°,钉道轴心距坐骨大切迹的距离为(1.05±0.81)cm,钉道轴心距髋臼上缘的距离为(1.85±0.33)cm,髂骨宽度为(2.12±1.65)cm。男性患者的钉道长度、外展角、尾倾角、钉道轴心距坐骨大切迹的距离、钉道轴心距髋臼上缘的距离、髂骨宽度分别为(12.40±0.83)cm、39.47°±1.76°、28.00°±6.39°、(1.08±0.32)cm、(1.76±0.34)cm、(2.26±0.25)cm;女性患者分别为(11.75±1.01)cm、42.30°±4.48°、27.56°±6.61°、(1.21±1.00)cm,(1.90±0.32 cm)、(2.04±0.18)cm。男性患者钉道长度、外展角与女性的差异有统计学意义(P<0.05)。女性患者的外展角、尾倾角与既往非ADS人群的文献报道相比具有外展角增大、尾倾角减小(P<0.05)。结论ADS患者具有理想的S2AI螺钉钉道轨迹,其螺钉长度与非ADS人群无明显差异,但其置入方向则存在差异,尤其女性患者。术中女性ADS患者置入S2AI螺钉时,应减小尾倾角、增大外展角。

Objective To discuss the imagingcharacteristics of S2AI screw trajectory in ADS patients.Methods Forty patients with degenerative scoliosis were scanned with Simens Sliding 40-slice spiral CT scanner.Three-dimensional scanning and reconstruction were performed in these patients with the scanning range including thoracolumbar spine,lumbar spine,lumbosacral region,pelvis and bilateral hip joints.The base of the lateral sacral crest on the midline between the lower edge of S1 dorsal foram-ina and the upper edge of S2 dorsal foramina was the starting point.The placement plane of S2AI screw trajectory was determined from the starting point to the lower margin of anterior inferior iliac spine.A 10mm diameter screw was the design template.A cir-cle with a diameter of 5 mm as the center of the lowest point of the ilium inner cortex was made,and a tangent line from the start-ing point to the outer diameter of the circle(the inner part of the ilium)was selected as the axis of the screw trajectory.The lateral angle and the length of the axis of the screw trajectory and iliac width were measured in transverse plane.The caudal angle,the distance from the axis of the screw trajectory to iliosciatic notch,and the caudal angle,the distance from the axis of the screw tra-jectory to the upper edge of the acetabulum were measured in sagittal plane.These parameters were recorded and analyzed.Re-sults The trajectory length of S2AI screw in ADS patients was 12.00±0.99 cm,the lateral angle was 41.24°±3.92°,the caudal an-gle was 27.73°±6.45°,and the distance from the axis of the screw trajectory to iliosciatic notch was 1.05±0.81 cm,the distance from the axis of the screw trajectory to the upper edge of the acetabulum was 1.85±0.33 cm,and the iliac width was 2.12±1.65 cm.The trajectory length,lateral angle,caudal angle,distance from the axis of the screw trajectory to iliosciatic notch,distance from the axis of the screw trajectory to the upper edge of the acetabulum and iliac width of S2AI screw was respectively 12.40±0.83 cm,39.47°±1.76°,28.00°±6.39°,1.08±0.32 cm,1.76±0.34 cm,2.26±0.25 cm in male patients,and was respectively 11.75±1.01 cm,42.30°±4.48°,27.56°±6.61°,1.21±1.00 cm,1.90±0.32 cm,2.04±0.18 cm in female patients.The screw length and later-al angle had statistically difference between male and female patients(P<0.05).Compared with non-ADS patients in previous stud-ies,female patients with ADS had significant differences in increased lateral angle and decreased caudal angle of S2AI screw.Con-clusion There is ideal trajectory of S2AI screws in ADS patients.There was no significant difference of the length of S2AI screws between ADS patients and non-ADS population.Different direction was noticed in the placement of S2AI screws,especially in fe-male patients.Increased lateral angle and decreased caudal angle would be obtained in the procedure of placing S2AI screws in fe-male ADS patients during operation.