Estimated ground reaction force in normal and pathological gait.

In clinical gait analysis, ground reaction force (GRF) is the gait parameter which can validate the state of disorder of the patient's movement. The purpose of this study was to explore the possibilities of employing the GRF derived from kinematics of the center of gravity (COG) in the study of dynamics of human gait. Gait data was collected for healthy able-bodied men and women and patients after ACL reconstruction who use larger lateral COG excursions during gait. Reasonable agreement between methods was found in fore-aft and vertical directions, where the methods differed by an average of less than 10% in either direction. Based on model predictions of the body's COG trajectory during walking, algorithms were developed to determine spatio-temporal gait parameters related to GRF characteristics. The suitability of calculating ground reaction forces using COG displacement in a patient population is questioned.