While the reliability of tibial torsion measurement techniques has been reported in adults, a comprehensive evaluation of techniques commonly used in children, in whom radiographic landmarks and torsional magnitude may vary with age, has not been reported. The primary aim of this study was to determine the inter-rater reliability of four proximal (posterior femoral condylar axis PFCA, femoral epicondylar axis FECA, tibial epicondylar axis TECA, posterior tibial axis PTA) and three distal (Jakob et al., Goutallier et al., Madadi et al.) methods for measuring tibial torsion in pediatric patients. The secondary aim was to assess differences in measured torsional magnitude amongst methods. Two attending pediatric orthopaedic surgeons, two senior orthopaedic residents, and two medical students performed four proximal and three distal measurements on 60 lower limb CT scans of patients ≤18 years obtained 7/20/2016-7/20/2022. Inter-rater correlation coefficients (ICC) were calculated with a two-way random model for absolute agreement across attendings and between attendings and trainees. Mean resultant tibial torsion for each combination of techniques was calculated. ICCs demonstrated that the PFCA and Jakob methods are the most reliable (Surgeon ICC: 0.992 and 0.983, respectively). PFCA, FECA, and PTA demonstrated equivalent excellent ICCs (0.989, 0.978, 0.968). Jakob, Goutallier, and Madadi also demonstrated excellent ICCs (0.987, 0.977, 0.951). All methods demonstrated excellent reliability besides TECA (ICC = 0.869, Table 1). The largest difference in mean resultant version, calculated via the largest magnitude (TECA/Madadi tibial torsion 48.1 ± 16.3°) and smallest magnitude (FECA/Goutallier tibial torsion 32.6 ± 15.8°) methods, was 15.5°. Tibial torsion measured in a pediatric sample may differ as much as 15.5° depending on technique used. A standardized method should be adopted. Three of the proximal measures demonstrated excellent reliability. While femoral measurements for tibial torsion rely on an assumption that the distal femoral alignment is a proxy for tibial alignment, PTA is a direct measure of the tibia and is our preferred proximal method. Distal methods all demonstrated excellent agreement. Due to simplicity of measurement and highest ICC, the Jakob method is our preferred distal method. This study did not assess accuracy, although PTA and Jakob were previously noted to be highly accurate. Tibial torsion may vary by 15.5° purely based on the technique utilized. A set of distal and proximal methods should be selected and used consistently. Given high reliability and prior reports of high accuracy, we recommend the PTA and Jakob methods for measurement of tibial torsion. For any figures or tables, please contact the authors directly.
Dodwell et al. (Wed,) studied this question.