Electronic measurement of instantaneous foot-floor contact patterns during gait

An automated system to study foot-floor contact weight bearing patterns has been developed. The system includes a contact area transducer with digital signal conditioning, force plate and minicomputer. The system is capable of measuring foot-floor contact areas, average contact pressure, speed of the center of pressure and vertical force in relation to the position of the resultant force under the foot. In addition, the system provides computerized images of the instantaneous foot contact areas and centers of pressure resulting in a composite foot contact area and the pathway of the center of pressure. A preliminary study, using the system, indicated several common features among the weight bearing patterns of normal subjects during gait. The highest contact pressures occurred in the region of the heel and metatarsal heads during heel strike and toe off respectively. The contact area under the foot increased with increasing vertical force producing a nearly constant average contact pressure through the midstance phase of gait. The highest speed of the center of pressure was found to occur in the region of the heel, while a pause in the progression of the center of pressure was observed in the region of the second and third metatarsal heads. In contrast to the other parameters the pathway of the center of pressure was found to have the greatest variations among test subjects. However, for repeated observations of a single subject the pathway was found to be reproducible.