Analysis of acetabular orientation and femoral anteversion using images of three-dimensional reconstructed bone models

PurposeRadiographic measurements using two-dimensional (2D) plain radiographs or planes from computed tomography (CT) scans have several drawbacks, while measurements using images of three-dimensional (3D) reconstructed bone models can provide more consistent anthropometric information. We compared the consistency of results using measurements based on images of 3D reconstructed bone models (3D measurements) with those using planes from CT scans (measurements using 2D slice images).MethodsNinety-six of 561 patients who had undergone deep vein thrombosis-CT between January 2013 and November 2014 were randomly selected. We evaluated measurements using 2D slice images and 3D measurements. The images used for 3D reconstruction of bone models were obtained and measured using $$\hbox {Mimics}^{\mathrm{\textregistered }}$$Mimics® and $$\hbox {3-Matics}^{\mathrm{\textregistered }}$$3-Matics® (Materialize, Leuven, Belgium).ResultsThe mean acetabular inclination, acetabular anteversion and femoral anteversion values on 2D slice images were 42.01$$^{\circ }$$∘, 18.64$$^{\circ }$$∘ and 14.44$$^{\circ }$$∘, respectively, while those using images of 3D reconstructed bone models were 52.80$$^{\circ }$$∘, 14.98$$^{\circ }$$∘ and 17.26$$^{\circ }$$∘. Intra-rater reliabilities for acetabular inclination, acetabular anteversion, and femoral anteversion on 2D slice images were 0.55, 0.81, and 0.85, respectively, while those for 3D measurements were 0.98, 0.99, and 0.98. Inter-rater reliabilities for acetabular inclination, acetabular anteversion and femoral anteversion on 2D slice images were 0.48, 0.86, and 0.84, respectively, while those for 3D measurements were 0.97, 0.99, and 0.97.ConclusionThe differences between the two measurements are explained by the use of different tools. However, more consistent measurements were possible using the images of 3D reconstructed bone models. Therefore, 3D measurement can be a good alternative to measurement using 2D slice images.