Contact force ratio: a new parameter to assess foot arch function.

Abstract

Static footprint parameters have been used to quantify arch height with conflicting results. This could be caused by the inherent inaccuracy and variations of the methodology used. Since the foot is a dynamic structure that undergoes changes during a step, it is more desirable to capture and analyse the dynamic footprint at an instant during the gait cycle that can most closely reflect the weight-bearing foot function. Forty (40) volunteer subjects were recruited for the reliability test of a new parameter, the Contact Force Ratio (CFR), derived from dynamic footprint. This is a measure of midfoot loading during gait. The mid-gait dynamic footprints were collected using a pressure sensing mat. Results of ICC tests showed that the CFR had good intratester (0.918) and intertester (0.909) reliability. The validity of the method was examined by correlating the parameter to the functional change in arch height, i.e. the Navicular Drop between the non-weight-bearing and weight-bearing conditions.