A new method for measuring hindfoot alignment: Reliability and temporal stability

Abstract

Objective: To evaluate the interobserver reliability and temporal stability of an adapted Van Dijk-Asaumi method for measuring coronal hindfoot alignment. Methods: A cross-sectional, analytical, and prospective study including 42 adults without clinically apparent foot deformities. Weightbearing radiographs were obtained in the anteroposterior, profile, and long axial views of the calcaneus. Hindfoot alignment was measured using a novel adapted method by Van Dijk-Asaumi and assessed by four evaluators with different levels of experience. Interobserver reliability and test-retest reliability were assessed using the intraclass correlation coefficient (ICC). The standard error of measurement (SEM) and the minimal detectable change (MDC) were also calculated. Additionally, Bland-Altman analysis was performed, and Lin’s concordance correlation coefficient was determined. Results: Interobserver reliability was moderate, with ICC values ranging from 0.54 to 0.61. Test-retest reliability demonstrated adequate temporal stability, with ICC values between 0.57 and 0.61. The SEM was low (0.12°-0.14°), with an MDC below 0.4°. Bland-Altman analysis revealed negligible systematic bias and narrow limits of agreement. Lin’s concordance correlation coefficient indicated nearperfect agreement (0.996-0.997). The adapted method demonstrated low measurement error and adequate temporal stability, though only moderate interobserver reliability (ICC 0.54-0.61). Conclusions: The novel method demonstrated low measurement error, adequate temporal stability, and moderate overall interobserver agreement, establishing itself as a practical, objective, and reliable alternative for the quantitative assessment of hindfoot alignment in clinical practice. Level of evidence III; Methodological, Cross-sectional, Analytical, and Prospective Study