股関節全置換術後の寛骨臼コンポーネント前方捻転角のコンピューテッドトモグラフィー解析：従来の軸方向および機能的冠状断面を比較する後向き研究

This study aims to compare the accuracy and reliability of computed tomography (CT) anteversion measurements between the conventional axial plane (CAP) and the functional coronal plane (FCP). We retrospectively examined 68 patients' postoperative CT scans following primary unilateral total hip arthroplasty (THA). PolyWare software, which uses edge detection to determine radiographic anteversion of the acetabular component, served as the reference standard. We measured anatomical anteversion in the CAP and radiographic anteversion in the reformatted FCP using reconstruction software. Reliability was evaluated with the intraclass correlation coefficient. The mean anteversion of the acetabular component in the CAP and FCP CT images were 29.18 ± 6.06° and 21.17 ± 5.38°, respectively. The mean CT anteversion in the FCP was considered accurate owing to its similarity with the reference standard (20.70 ± 4.39°, P = .281). However, the mean CT anteversion in the CAP was significantly different and thus considered less accurate; the CT anteversion in the CAP was larger than that in the FCP, showing a significant linear correlation (R = 0.673, P < .001), with a difference of 8.01°. The intraobserver and interobserver reliabilities were excellent for all measurement methods. Using radiographic anteversion defined by digital image analysis software as the reference standard, the anteversion measurement in the reformatted FCP proved more accurate than in the CAP. The reformatted FCP CT image facilitates precise post-THA anteversion measurement, with the method difference being around 8.01°. This study aids in measuring anteversion via CT.