64排螺旋CT三维重建对确定椎板关节突螺钉钉道的作用分析

Translaminar facet screw:an anatomical study by 3D CT

目的介绍一种在螺旋CT上测量经皮椎板关节突螺钉长度和方向的方法,为该螺钉的微创置入提供影像学指导。方法随机选取腰骶椎64排CT扫描数据30例。对扫描数据行三维重建,在重建的图形上确定螺钉的进钉点和出钉点,建立螺钉空间走行立体图形,利用几何知识测量、计算得到椎板关节突螺钉钉道的长度、外侧倾斜角(与矢状面的夹角)和尾侧角(与横断面的夹角)。结果在重建图形上根据拟定的椎板关节突螺钉进、出点可以构建理想的螺钉空间走行立体图形,并能准确计算出钉的长度和方向。从L1/2到L5/S1:椎板螺钉钉道逐渐增长,为43.2±2.0～53.7±2.6mm;钉道的内倾角逐渐增大,为40.7±1.40～44.7±1.90;尾侧角逐渐减小,为27.5±1.60～23.0±2.20。结论在螺旋CT三维重建上能准确计算出手术时所需椎板关节突螺钉的长度,可以精确地拟定术中螺钉的方向,从而为术前椎板关节突螺钉的选择和术中进钉方向的确定提供影像学依据。

Objective To introduce a method of the theoretical basement for clinical application of the percutaneous translaminar facet screw for measuring the length and orientation of the instrument by CT.Methods 30 CT datas of lumbosacral sections were elected randomly.The screw path was defined on CT previously.A stereograph was then constructed with the path as a diagonal.On the basis of the graph, from L1/2 to L5/S1,the screw path length,caudal and lateral angles were measured respectively.Results The stereograph was constructed successfully.The length and orientation of the path were counted accurately.The mean values of the length （43.2±2.0～53.7±2.6mm）and lateral angle （40.7±1.40～44.7±1.90）gradually increased from L1/2 to L5/S1,but the caudal angle （27.5±1.6°～23.0±2.2°） gradually decreased.Conclusion The length and orientation of the percutaneous translaminar facet screw can be determined by CT, which can benefit the surgical procedure.