应用三维重建测量股骨颈前倾角的计算机方法研究

Computerized approach for 3D-reconstruction measurement of femoral neck anteversion

目的寻求一种测量结果更符合真实前倾角值的测量方法。方法应用计算机重建股骨CT断层图像获得三维模型,将股骨头拟合成球体以确定股骨头中心;然后截取股骨颈区域并重新分割为断层图像,测量每层的体积进行比较以确定股骨颈峡部,从而确定股骨颈中心;经三维模型表面直接选取内、外髁。结果股骨头中心、股骨颈中心的连线即为颈轴线,内、外髁的连线即为髁状轴,根据Billing对前倾角的定义,两线所形成的夹角即为前倾角。结论该研究符合定义法测量,故测量结果更为可信。

Objective To explore a new precise method for measuring the femoral neck anteversion（FNA）.Methods The three-dimensional reconstruction model of the femur by Mimics software based on the CT images was obtained.The femural head was reshaped as sphere to determine the head center.Then separated the neck region from the full model and cut this area into different layers to determine the neck isthmus.Two points as lateral apex of the posterior femoral condyle（LAPC）and medial apex of the posterior condyle（MAPC）were selected directly through the surface of the model.Results The connecting line of the centers between femoral head and neck was defined as femoral neck axis,while the connecting line of LAPC and MAPC was defined as condyle axis.According to Billing＇s definition on FNA,the angle between these 2 lines was FNA.Conclusion It is demonstrated that the method essentially belongs to the definition method described by Billing,thus the measurement result is more reliable.