Computed Tomography in Evaluation of Femoral Anteversion: Transverse Section Versus Axial Oblique Section

Abstract

This study was aimed to define a more accurate computed tomography (CT) scanning method for measurement of the anteversion angle of the femoral neck. Five models of the femur, consisting of three models of saw bones and two of cadaveric bones, were used to measure femoral anteversion. Real femoral anteversion was measured with photographs taken from the superior aspect of the femoral neck after placing the specimen in the position that both posterior condyles rested on the surface of the table and the center of the femoral head and center of the intercondylar notch were aligned in a single line. Femoral anteversion using the transverse section of CT (CT1) and the axial oblique section of CT (CT2) were obtained. Three experienced orthopedic surgeons measured the anteversion of five bone models using the photographs and two CT scans, three times each with a week interval between measurements. A total of 45 measurements were obtained. The intraclass correlation coefficient (ICC) was used to compare anteversion measurements between the different methods. Femoral anteversion measured in photographs was correlated with measurements on CT1 and CT2. However, CT2 more closely approximated the real anteversion than did CT1 (ICC; CT1 = 0.824, CT2 = 0.937). Inter-observer and intra-observer biases were not found (ICC ≥ 0.952). The axial oblique image more closely approximated the real femoral anteversion than did the transverse sectional image. Measurement of femoral anteversion using axial oblique CT is recommended over conventional transverse sectional CT.