The analysis of ground reaction forces in pathological gait secondary to disorders of the foot.

A description is given of the vertical and horizontal components of the forces applied to the floor by the foot in walking. Information about the characteristics of the normal force pattern was obtained from the analysis of the gait of 214 normal subjects (108 young adults, 63 elderly people and 43 children). It is suggested that the normal gait pattern is characterised by a marked population variability, a considerable step-to-step consistency and symmetry of the forces from both feet. The force pattern in pathological gait secondary to disorders of the foot also shows a marked repeatability but is characterised by a pronounced asymmetry. A specific disorder of the foot does not necessarily result in a typical corresponding force pattern. The measured data allow a functional diagnosis and show how the patient is reacting to his disability. A force visualisation system is proposed permitting the immediate comparison between the normal and the affected foot and allowing long term assessment of subsequent changes. The force plates used also allow the recording of the progression of the centre of pressure in the foot and the measurement of the torque around the ankle joint.