Mesgarzadeh M, Revesz G, Bonakdarpour A
Department of Diagnostic Imaging, Temple University, Hospital and School of Medicine, Philadelphia, PA 19140.
J Comput Assist Tomogr. 1987 Sep-Oct;11(5):799-803. doi: 10.1097/00004728-198709000-00011.
To establish the accuracy and reproducibility of measuring femoral neck torsion angles (FNTA) on CT images, this angle was measured on 12 dry femora directly on the gross specimens, on plain radiographs, and on CT images. The selection of the CT level, both at the femoral neck and the condyles, that may affect the measurement of FNTA was analyzed. The CT measurements of FNTA were found to have a reproducibility of 2.5 and 0 degrees mean offset error when compared with readings on plain radiographs. A new CT method was developed to measure this angle particularly in patients with coxa valga in whom this measurement is difficult if not impossible to accomplish by current methods. For this purpose composite CT images were made of the femoral head and the femoral shaft, immediately below the lesser trochanter. On these images the line connecting the centers of the femoral head and shaft were inferred to represent the cervical plane. In comparison with the standard CT method, this new method had the same reproducibility, although it slightly overestimated this angle by 2 degrees. This degree of error is negligible when compared with the normal variations of this angle, which ranges from -20 to +38 degrees. Furthermore, it compares favorably with the limited accuracy of derotational osteotomy surgery.
为确定在CT图像上测量股骨颈扭转角（FNTA）的准确性和可重复性，分别在12具干燥股骨的大体标本、X线平片及CT图像上测量该角度。分析了可能影响FNTA测量的股骨颈及髁部CT层面的选择。与X线平片测量结果相比，发现CT测量FNTA的可重复性为2.5，平均偏移误差为0度。开发了一种新的CT方法来测量该角度，特别是对于髋外翻患者，目前的方法很难甚至无法完成该测量。为此，在小转子下方紧邻处制作了股骨头和股骨干的复合CT图像。在这些图像上，连接股骨头和股骨干中心的线被推断为代表颈平面。与标准CT方法相比，这种新方法具有相同的可重复性，尽管它将该角度略微高估了2度。与该角度-20至+38度的正常变异相比，这种误差程度可以忽略不计。此外，与旋转截骨手术有限的准确性相比，它具有优势。
