Classification of foot type from Podography: Correlation of results between six quantitative assessment methods

Abstract

Objective: Apply the different methods available in the literature to classify a sample of podography and evaluate the level of agreement between the results. Methods: Six quantitative methods and one qualitative method for classifying foot type from podography were recorded on 30 feet. The podography indexes were calculated and the level of agreement between methods was explored. Results: Correlation values were above r=0.84 except for the test Arch Footprint Angle. The highest correlation values were found between Truncated Arch Index and Footprint Index (0.99), Arch Index and Footprint Index (-0.94) and Arch Index and Truncated Arch Index (-0.94), and the lowest was the Arch Footprint Angle with the other parameters. However, there was a difference in the classification between the foot types, indicating a lack of agreement of thresholds between foot types. The faster method for the classification of foot type was the qualitative Visual Inspection. Conclusion: The Visual Inspection proved to be the fastest test to be applied followed by the quantitative Arch Footprint Angle test. High correlation values were found between tests, especially between the Arch Index and the Footprint Index, Arch-length Index, Truncated Arch Index and Chippaux-Smiraak Index tests.