髋臼后部骨折顺行拉力螺钉固定进钉导航模板的可行性研究

Feasibility study of navigational template for antegrade lag screw fixation of the fractures in the posterior column of acetabulum

目的探讨导航模板辅助顺行托力螺钉蚓定髋闷后部骨折的可行性与实用性。方法收集40例正常成人骨盆的螺旋CT扫描数据，导入Mimics10．01软件重建骨盆三维模型。选取左侧半骨盆模型，经过坐骨结节沿着髋臼后柱纵轴置人虚拟圆柱体。调整圆柱体位置，确定最佳进钉点，分别测最进钉点到弓状缘、骶髂关节最前缘的最短距离、圆柱体与冠状面夹角α、四方区与髂翼所在平面的夹角β。以stI格式导出模型，UG6．0软件打开骨盆三维模型，定位参考平面。根据测量得到的进钉解剖学参数，确定后柱螺钉的最佳钉道。提取方形区及髂窝的表面解削学形态，建立与方形区解剖学形态一致的模板。设计出带有3个进钉孔的左侧髋臼导航模板模型，运用UG软件镜像功能生成右侧髋臼导航模板模型，利用快速成形技术生成实体模型。取16具（男7例、女9例）干燥的人体左侧骨盆标本，模拟从小同的进钉孑L进行髋臼后柱螺钉的置人，验证导航模板辅助进钉的准确性。结果成功地设计并制作出与四方区解剖结构较一致的导航模板。不同的进钉孔进钥‘成功率：进钉孔1，6.3％（1具）准确定位、75％（12具）良好定位、18．7％（3具）失败；进钉孔2，81．3％（13具）准确定位、18．7％（3具）良好定位；进钉孔3，37．5％（6具）准确定位、62．5％（10具）失败。结论根据髋臼后柱拉力螺钉进钉解剖学参数设计的导航模板可以准确地辅助拉力螺钉的置入。

Objective To analyze the feasibility and practicality of the navigational template for antegrade lag screw fixation of the fractures in the posterior column of acetabulum. Methods Spiral CT scan data of 40 normal aduh pelvis was collected. 3D CT scans of pelvics were performed. Virtual 3D pelvic models were reconstructed with software Mimics 10.01. Virtual cylindrical implants were placed along the longitudinal axis of the acetabular posterior column via the ischial tuberosity among the ipsilateral hemipelvis and some anatomical parameters were measured. To adjust cylinder position to determine the best projectinn point, the shortest distance of the point to the linea terminalis and the anterior border of the auricular surface, the angle between the cylindrical and the coronal plane （α）, and the angle between the quadrilateral district and lilac fossa plane （β ） were measured respectively. The 3D models were imported into software UG 6.0. The models of navigational templates were designed according to the anatomic： features of the acetabulums and the measured parameters. 16 cases of dry left side of pelvis specimens were collected. Sim- ulate aeetabular posterior column screw fixation from different screw holes and verify the accuracy of navigation template assisted in the nail. Results The navigational templates was designed and manufactured successfully which was more consistent with the anatomical features of the quadrilateral plane. Placement of lag screw from the first hole： 6.3% achieved accurate positioning, 75% well positioning, and 18.7% loose. From the second hole： 81.3% had accurate positioning, 18.7% well positioning. From the third hole： 37.5% had accurate positioning, 62.5% loose. Conclusion The navigational template designed according to the anatomic features of acetabulum and the measured parameters can accurately assist lag screw placement.