A framework for robust spatiotemporal analysis of dynamic plantar pressure measurement over the stance phase of gait.

Abstract

Barefoot plantar pressure assessment commonly involves discrete regional sampling from maximum pressure distributions measured over the stance phase of gait. This approach fails to capture spatiotemporal variation in plantar pressures across a spectrum of foot morphologies. Here we introduce a framework for systematically evaluating spatiotemporal plantar pressure distributions. Plantar pressures measured over stance are linearly interpolated into 5%-time instance pressure distributions. The foot progression angle is determined using the maximum pressure distribution and used to rotate each interpolated 5%-time instance pressure distribution. A bounding region capturing the entire maximum pressure distribution is used to scale each 5% distribution to a standardized 50 × 18 grid using a force preserving approach. Reliability was assessed in individuals with structurally altered (n = 10) and healthy (n = 10) feet. Intraclass Correlation Coefficients (ICCs) were calculated for foot progression angle, minimum detectable change (MDC) for maximum pressure at each grid location, and a linear mixed effects model with Bland-Altman plots for mean pressures between original and aligned intervals. All ICC values were greater than 0.85 with an MDC of 9.05 ± 10.79 kPa across the entire grid. The linear mixed effect model and Bland-Altman plots demonstrated a significant systematic framework bias of 9.91 ± 2.05 kPa (p < 0.001) and 8.58 ± 1.88 kPa (p < 0.001) for healthy and structurally altered feet, independent of stance interval, foot size, or foot progression angle. These data suggest the framework can be used to reliably assess plantar pressures in structurally altered feet, enabling robust comparison of spatial pressure distributions during gait.