Procedure for quantitative comparison of ground reaction data.

Measurement of ground reaction forces has been largely adopted for evaluation of gait disorders even if the discussion of obtained results and their comparison with those from normal locomotion are generally related to a purely visual interpretation of the pattern morphology or, at least, to the assessment of a limited number of parameters such as maximal amplitude of force, number of maxima in the envelope, presence of one minimum or more, etc. This paper describes an analytical method for a quantitative and detailed comparison of different ground reaction force patterns. It is based on a suitable processing of the 3-D components of the ground reaction force and is essentially composed of three main frames: verification of the regular recurrence of measurement conditions, normalization, and data comparison. The first frame is to check that the acquired data are not affected by inertial predominance in the direction of progression. Normalization involves the amplitude of force, the application point displacements and the stance-phase duration. Data comparison utilizes a dedicated implementation of an appropriate statistical approach to estimate significant differences between two suitable and typical ground reaction force patterns. In order to show practical examples of the whole analytical procedure, two cases are also presented in detail.