Computed Tomography Analysis of Acetabular Component Anteversion after Total Hip Arthroplasty: Conventional Axial versus Functional Coronal Plane

Aims: This study aimed to compare the accuracy and reliability of computed tomography (CT) anteversion measurements between the conventional axial plane (CAP) and functional coronal plane (FCP). Methods: We retrospectively reviewed 68 patients who underwent primary unilateral total hip arthroplasty (THA) and postoperative CT. Values obtained using PolyWare software were considered the reference standard. The anteversion of the acetabular component was measured in the CAP as anatomical anteversion and in the reformatted FCP as radiographic anteversion using a reconstruction software. Reliability was assessed using the intraclass correlation coefficient. Results: The mean anteversion of the acetabular component in the CAP and FCP CT images was 29.18° ± 6.06° and 21.17° ± 5.38°, respectively. The CT anteversion measurement was more accurate in the reformatted FCP than in the CAP owing to its similarity with the reference standard (20.70° ± 4.39°, p = 0.281). The CT anteversion was larger in the CAP than in the FCP, showing a significant linear correlation and a difference of 8.01°. The intra- and interobserverreliabilities were excellent for all measurement methods. Conclusion: The reformatted FCP CT image is useful in the accurate measurement of anteversion after THA. This study will also help measure anteversion through CT.