Accuracy of 2D CT-Based Measurements of Rotational Alignment of the Femoral Component for Total Knee Arthroplasty

• Published in: Yonsei medical journal Vol. 62; no. 5; pp. 439 - 445
• Main Authors: Park, Jun Young, Kwon, Hyuck Min, Cho, Byung Woo, Lee, Woo-Suk, Yang, Ick Hwan, Park, Kwan Kyu
• Format: Journal Article
• Language: English
• Published: Korea (South) Yonsei University College of Medicine 01.05.2021; 연세대학교의과대학
• Subjects: Arthroplasty, Replacement, Knee; Femur - diagnostic imaging; Femur - surgery; Humans; Knee Joint - diagnostic imaging; Knee Joint - surgery; Original; Osteoarthritis, Knee - surgery; Reference Values; Rotation; Tomography, X-Ray Computed; 의학일반; Knee; total knee arthroplasty; 3D reconstruction; 2D-CT; osteoarthritis; rotational alignment of the femoral component
• ISSN: 0513-5796; 1976-2437; 1976-2437
• DOI: 10.3349/ymj.2021.62.5.439

We aimed to investigate the accuracy of two-dimensional computed tomography (2D-CT)-based methods for measuring rotational alignment of the femoral component during total knee arthroplasty in comparison to reference values for three-dimensional (3D) reconstruction. We selected the "most protruding transepicondylar axis section," "most protruding posterior condylar line section," and "distal femoral cut section" on 2D-CT images for 100 knees. We investigated posterior condylar angle (PCA) and condylar twist angle (CTA) values using three different methods on 2D-CT and compared to these values to those obtained using a 3D model. The mean PCA and CTA values were 2.8° and 7.0° on the 3D model and 2.0° to 2.1° and 5.9° to 6.0° on 2D-CT, respectively. Errors in PCA and CTA measurement included internal rotation of 0.8° and 1.1° with the 1-plane and 2-plane methods and 0.9° and 1.0° with the assumed resection method, respectively. Mean errors in PCA and CTA values measured using three different methods on 2D-CT were not significantly different. However, PCA and CTA values measured on 2D-CT were approximately 1° smaller than their 3D values. Thus, we suggest that adding 1° to the mean PCA and CTA values obtained from a single plane of 2D-CT would provide values similar to those obtained from 3D reconstruction.