Arch index measurement method based on plantar distributed force

In this paper, the solution method for foot arch index (FAI) based on plantar force measurement was proposed. The entire pelma (EP) was divided into three partitions: posterior heel (HP), lateral side of the sole (SL) and medial side of the sole (SM) according to the three-point support mechanics mechanism of the foot and ankle. A distributed force platform was established to obtain the mean positions of the center of pressure (CoP) trajectories on SL, SM, HP, and EP, which were defined as A, B, C, and O, respectively. Based on the principle that the arch height influences the distance from point O to the boundary of triangle ABC, the area ratio of triangle BOC to triangle ABC was defined as FAI. Arch height index (AHI) measurement of thirty participants by combined calipers was compared with FAI measurement of their right feet. The arches were classified based on AHI, and ANOVA was performed. The Pearson correlation coefficient between the FAI method and the AHI method is 0.79 (p＜0.0001). The Bland-Altman analysis showed good agreement. ANOVA indicated FAI was statistically significant (F = 18.81,p＜0.001), and there were statistical differences between groups. These results suggest that the proposed distributed force measurement method can provide support surface boundary (triangle ABC) information related to point O.