Reliability of the figure-of-eight method for measuring foot and ankle edema: Prospective emergency department assessment and literature review

Abstract

Objective: This study aimed to evaluate the inter- and intra-rater reliability of the figure-of-eight (FoE) method for measuring foot and ankle edema when performed by emergency medicine and orthopedic residents in the emergency department (ED). Methods: This prospective observational study was conducted at the ED of a tertiary hospital between November 2024 and January 2025. A total of 102 adult patients with foot or ankle trauma (51 males and 51 females) were included. The mean age was 38.1 Å} 13.1 years. Twenty residents (10 orthopedic and 10 emergency medicine residents) performed FoE measurements. Each patient underwent eight measurements, with two repeated measurements by two raters from each specialty. The primary outcome measures were inter- and intrarater reliability, assessed using intraclass correlation coefficients (ICC) with 95% confidence intervals, as well as the standard error of measurement (SEM) and minimal detectable change (MDC). Results: A total of 102 patients were analyzed. Intra-rater reliability was excellent for both emergency medicine residents (ICC = 0.987, 95% CI: 0.980–0.991, p < 0.001) and orthopedic residents (ICC = 0.984, 95% CI: 0.977–0.990, p < 0.001). Inter-rater reliability was also excellent for emergency medicine residents (ICC = 0.968, 95% CI: 0.953–0.978, p < 0.001), orthopedic residents (ICC = 0.960, 95% CI: 0.941–0.973, p < 0.001), and between both specialty groups (ICC = 0.951, 95% CI: 0.928–0.967, p < 0.001). SEM ranged from 0.57 to 1.12 cm, while MDC ranged from 1.57 to 1.75 cm for intra-rater reliability and from 2.46 to 3.10 cm for inter-rater reliability. Conclusion: The FoE method demonstrated excellent inter- and intra-rater reliability for bedside assessment of foot and ankle edema in the emergency department. These findings support its use as a simple, inexpensive, and standardized tool for reproducible clinical assessment by both orthopedic and emergency medicine residents. The method may facilitate consistent serial evaluation of patients with acute foot and ankle trauma in routine emergency practice. Further studies are warranted to evaluate its criterion validity and responsiveness.   Cite this article as: Altan SM, Yesilaras M, Ocak NY, Parlar O. Reliability of the figure-of-eight method for measuring foot and ankle edema: prospective emergency department assessment and literature review. Acta Orthop Traumatol Turc., 2026; 60(5), 0962, doi: 10.5152/j.aott.2026.26962.