Analyzing plantar pressure trajectories is crucial for assessing foot behavior in dynamic gait stability. We propose the identification of foot symmetry and the detection of deformities by analyzing the trajectories of the center of pressure (CoP) and peak pressure (PP). First, using a foot pressure mapping system, plantar pressure data are acquired during a normal gait cycle. After the data have been acquired, post processing extracts both the CoP and PP trajectories over the spatiotemporal domain of foot motion for each foot independently. For this purpose, we used the optical flow technique which accurately estimates the direction of foot motion. The extracted trajectories of each foot are then segmented into, the medial and lateral regions. This segmentation is essential for assessing symmetries and deformities of the foot. Our focus is on two types of foot deformities, flat and high-arched which are compared with a control population that we used to evaluate any errors in our proposed approach. The results show that our hybrid symmetry index, which includes CoP and PP trajectories along the butterfly medial region, has better sensitivity than traditional metrics. The medial region analysis thus seems to more effective at distinguishing between pathological and normal gait patterns
