Correlation between plantar pressure and foot morphology in 65 + year-old individuals

The purpose of this study was to determine the correlation between plantar pressure (PP) and clinically easy-to-measure foot morphology parameters in 65 + year-old individuals.

Sixty-two 65 + year-old individuals (28 males and 34 females) participated in the experiment. Three foot morphology parameters were measured: hallux valgus angle, navicular height (normalized by foot length), and calcaneal angle. Participants walked at a self-selected comfortable speed along a 6-meter walkway. PP was measured as they passed over a 2-meter platform located at the walkway midpoint. Correlations between foot morphology and PP were assessed using two types of partial correlation analyses with body weight as a covariate: region of interest (ROI) analysis and statistical parametric mapping (SPM).

ROI and SPM results showed broadly similar correlation trends between PP and hallux valgus angle, with significant positive correlations in the lateral metatarsals. However, navicular height correlations differed substantially: (1) while SPM found significant positive correlations across several foot regions, ROI results did not reach significance, and (2) while ROI analysis found a significant negative correlation in the medial midfoot, SPM found this effect to be non-significant.

Significant positive correlations observed between hallux valgus and PP may suggest a lateral loading shift with increased hallux valgus in 65 + year-old individuals. SPM found broad positive correlations between the navicular height and PP, indicating general increased load on foot portions distal and proximal to the longitudinal arch. ROI results failed to find this correlation significant, which agrees with previous reports that ROI analysis can distort pixel-level trends.