A method for computing the Functional Ambulation Profile score by stereophotogrammetric data

The Functional Ambulation Profile (FAP) Score is a performance index based on the assessment of selected time and distance parameters, during standard gait test. FAP is considered a reliable global parameter for gait evaluation. The first and original FAP score is provided in an automatic way by the GAITRite System, a portable electronic mat embedded with pressure-activated sensors. The present study was designed to achieve a FAP score computation which could be independent from its native environment, and could be implemented by means of classic gait analysis systems, as stereophotogrammetry. This goal was pursued computing the parameters, which FAP definition is based on, by means of processing of stereophotogrammetric data. The reliability of FAP computation was tested by direct comparison with the original GAITRite FAP score, in a single subject, during different walking trials (comfortable gait, very slow gait; very fast gait) and simulating several pathological gaits (gait with small step; “foot-drop” gait; “festinating” gait; “spastic” gait). No relevant differences detected between stereophotogrammetry-based and GAITRitebased estimates indicate that the proposed method is able to provide a reliable assessment of FAP in different kind of natural/pathological walking. The capability of FAP index to identify alterations of walking is also preserved. In conclusion, this study proposes the stereophotogrammetry-based computation of FAP as a valid alternative to the original GAITRite FAP. The convenience of an easy integration with classic stereophotogrammetry-based gait analysis parameters, supports the usefulness of stereophotogrammetry-based FAP in providing a complete picture of subject walking, without needing a further measurement system.