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Updated: Oct 5, 2026
An Anatomical Study of Nerves at Risk During Minimally Invasive Hallux Valgus Surgery
Published on: February 17, 2018
Neck vs head interspace ratios in hallux valgus: A reliability analysis of first metatarsal radiographic measurements
Miguel Viana Pereira Filho1, Gabriel Ferraz Ferreira1, Peter Lam2
1Department of Orthopaedics and Traumatology, Prevent Senior, São Paulo, Brazil; Instituto Vita, São Paulo, Brazil; Department of Orthopedics, Rheumatology and Traumatology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.
Background:
The relationship between the intermetatarsal space and first metatarsal width has been proposed as a radiographic parameter for surgical planning in hallux valgus. However, the reproducibility of the previously described Head Interspace Ratio (HIR) has not been formally evaluated, limiting confidence in its clinical application.
Purpose:
To compare the intraobserver and interobserver reliability of the Head Interspace Ratio (HIR) and the newly proposed Neck Interspace Ratio (NIR).
Study Design:
Retrospective cross-sectional reliability study.
Methods:
Fifty standardized weight-bearing anteroposterior radiographs were independently evaluated by three observers with different experience levels during two sessions. Reliability was assessed using intraclass correlation coefficients (ICC). Agreement and measurement precision were evaluated using Bland-Altman analysis, standard error of measurement, and minimal detectable change at the 95% confidence level.
Results:
NIR demonstrated good to excellent intraobserver reliability (ICC, 0.876-0.963) and good interobserver reliability (ICC = 0.886; 95% CI, 0.826-0.929). HIR showed greater variability, with good reproducibility for the two more experienced observers but poor reliability for the least experienced observer (ICC = 0.236; 95% CI, -0.043 to 0.481). Interobserver reliability was lower for HIR (ICC = 0.464; 95% CI, 0.276-0.633). Measurement error was lower for NIR than HIR (MDC95, 0.167 vs 0.277).
Conclusions:
Under the conditions evaluated in this study, NIR demonstrated greater reproducibility and lower measurement error than HIR. These findings suggest that NIR may represent a more robust radiographic parameter and support further clinical investigation before its use in surgical decision-making for hallux valgus.
