Comparison of Arch Index Derived from Optical Pedography and Barometric Platform in Children: A Method Agreement Study

Objectives: The Arch Index (AI) is commonly used to assess medial longitudinal arch morphology; however, values obtained using different measurement technologies may not be interchangeable. This study aimed to compare AI values derived from optical pedography and a barometric platform during bilateral static stance assessment in children and to evaluate their agreement. Methods: Thirty-eight healthy children aged 5–10 years underwent standardized bilateral static foot assessment. AI was calculated using identical segmentation and formula for both systems. Paired t-tests, Pearson correlation, intraclass correlation coefficient, and Bland–Altman analysis were used to assess agreement between methods. Results: Optical pedography produced significantly higher AI values than barometric assessment for both the left (0.284 ± 0.055 vs. 0.188 ± 0.092) and right foot (0.286 ± 0.048 vs. 0.169 ± 0.072; p < 0.001). Agreement between methods was moderate (ICC = 0.494–0.581), with wide limits of agreement. Inter-method differences increased with age. Conclusions: AI values obtained from optical pedography and barometric platforms are not interchangeable in children. Consistent use of a single measurement technology is recommended in pediatric assessment to avoid misinterpretation of developmental changes.