Pedobarographic Foot — Pressure Measurements and Their Applications

The pedobarograph is a device displaying and recording the instantaneous distribution of the pressure under the entire surface of the soles of the feet. The subject stands or walks on a transparent plate, in which light is conducted by total internal reflections. A plastic foil with a fine surface texture or a sheet of plastic foam is inserted between the foot and the plate. Under the resulting pressure the foil establishes contact with the plate and the light escapes with an intensity proportional to the pressure applied. Thus the pressure distribution pattern is converted to a light intensity picture and reflected back through the plate from where it can be observed or recorded. The device can be calibrated. The sensitivity and accuracy depend upon the type of foil used. Using closed circuit TV, an intensity level analyser can be inserted between the camera and the monitor, and the picture can be converted to an isobaric map. The pressure distribution is shown with each zone represented by a different colour. Addition­ally, the device can be adapted for graphical and digital display of the centre of gravity, as an indicator of balance. Some of the past and projected applications in therapeutic diagnostic use are given, including mass screening of feet, testing of shoe and insole design and balance studies.