FP7.3 Comparing Conventional 2D CT-Based Femoral Version Measurements and a 3D CT-Based Method in Hip Preservation Surgery: Which is the best match?

Abstract

Abstract ICLB07 - The Digital Surgeon: Practical Tools and Navigation Basics for Your Everyday Practice, Session Room 12 (BMCC Level 3), October 8, 2026, 14:00 - 16:00 Background Accurate assessment of femoral version is essential in hip preservation surgery, influencing diagnosis, surgical planning, and correction of femoral torsional abnormalities. Several conventional two-dimensional computed tomography (2D CT) methods are commonly used, including the Reikeras, Murphy, and Jarrett techniques. However, their agreement with emerging three-dimensional CT-based methods remains uncertain. Replasia is a 3D CT-based platform designed to provide anatomical assessment hip and pelvis parameters version through three-dimensional reconstruction. Purpose To compare conventional 2D CT methods for femoral version measurement with a 3D CT-based method (Replasia) and determine which 2D technique demonstrates the highest concordance. Methods A retrospective imaging study was performed on 62 hips from 31 consecutive patients evaluated for hip preservation surgery at a tertiary referral center. Mean age was 31.8 ± 9.6 years, and 18 patients (69%) were female. Indications for imaging included femoroacetabular impingement syndrome, borderline dysplasia, acetabular dysplasia, and symptomatic version abnormalities. Femoral version was measured on CT scans using Reikeras, Murphy, and Jarrett methods, and compared with the Replasia 3D CT-based measurement. Agreement was assessed using Lin’s concordance correlation coefficient (CCC) and Bland–Altman analysis. Results 30 hips from 15 patients were available for final analysis. Reikeras demonstrated the highest concordance with Replasia (CCC 0.927, 95% CI 0.856–0.964), with a mean bias of 1.38° and 95% limits of agreement from −5.99° to 8.76°. Murphy showed moderate concordance (CCC 0.801, 95% CI 0.636–0.896), with a mean bias of 4.92° and limits of agreement from −5.22° to 15.07°. Jarrett demonstrated similar performance (CCC 0.800, 95% CI 0.647–0.891), with a mean bias of 4.77° and limits of agreement from −4.69° to 14.23°. Both Murphy and Jarrett showed greater systematic deviation from Replasia than Reikeras. Conclusion Among conventional 2D CT methods, the Reikeras technique demonstrated the strongest agreement with the Replasia 3D CT-based femoral version measurement. Murphy and Jarrett methods showed lower concordance and greater measurement bias. Reikeras may represent the most reliable conventional 2D CT surrogate when 3D CT-based analysis is unavailable.