Arch indexes from ink footprints and pressure platforms are different

The pressure platform closely estimated contact areas for the heel and forefoot. Midfoot areas were underestimated sufficiently to bias the AI towards lower values. Therefore, the AI derived from a capacitance pressure platform is not the same as that from an ink footprint, and the two should not be used interchangeably. Feet classified according to AI from a pressure platform may be categorised differently than they would by using ink footprints. Pressure platform data cannot be used to determine AI with confidence until relative measurement error for isolated foot regions has been determined, or appropriate normative values established.