Quantifying differences in high-pressure region mapping between dynamic in-shoe and barefoot plantar pressure in diabetic subjects

Abstract

Foot ulceration is a serious complication of diabetes, often linked to elevated forefoot pressures during walking. Custom accommodative insoles reduce peak plantar pressures, with greater reductions achieved when dynamic pressure data informs design. While in-shoe and barefoot data are used separately to design insoles, their agreement in pressure distribution and high-pressure region location has not been evaluated. This study compares pressure distribution and high-pressure region mapping between in-shoe and barefoot data.

In-shoe and barefoot pressures were recorded during walking for 25 feet from 16 individuals with high forefoot pressures. High-pressure regions were masked, grouped, and labeled by anatomical region. In-shoe and barefoot pressure maps were averaged over trials and overlaid, and peak pressure and contact area were calculated for all high-pressure regions. For matched regions, centroid locations were compared.

In-shoe high-pressure regions (>200 kPa) were typically observed in similar locations to barefoot walking, while barefoot maps often identified additional regions (>450 kPa) in the toes and lateral forefoot. For in-shoe data, these regions had lower peak pressures and larger contact areas. Matched regions’ centroid positions differed by 0.23–0.60 cm.

Key loading areas were consistent between systems, though unmatched regions were common, particularly in barefoot data, reflecting greater sensitivity to localized pressures. Barefoot data may overestimate high-risk regions that do not display elevated in-shoe pressures. Basing offloading insole design on threshold-based barefoot high-pressure regions could reduce specificity and limit pressure reduction for in-shoe high-pressure regions. These findings have potential implications for streamlining clinical workflows during pressure-informed insole design.