Quantification of gait abnormalities on the basis of continuous foot-force measurement: correlation between quantitative indices and visual rating

Abstract

Although various methods have been proposed for quantitative evaluation of pathological gait, they are not yet widely used as routine clinical tools. The reasons are that measuring systems are too expensive and complicated and that the validity of the methods has not been fully examined in a statistical manner. In this paper, the validity of a new evaluation method based on a simple foot-force measuring device is investigated in terms of the correlation between quantitative indices and visually-rated grades. Forty-eight hemiparetic patients secondary to cerebral vascular accident walked on a 15 m straight level floor. Four people independently evaluated each subject in eight gait characteristics or items on a scale of 1–4 grades on the basis of visual inspection. These items include symmetry, variation, fluctuation, and dependence on the cane. At the same time, the vertical ground-reaction forces exerted on the right and left feet and on the cane were measured, and then quantitative indices representing these eight items were derived. All but one index shows a reasonably good correlation with the mean of the grades of the four observers. Thus, the feasibility of these indices is demonstrated. Statistical analysis also reveals several problems inherent in visual rating, such as inconsistency in the interpretation of evaluation criteria among observers, and a degradation of the independence of items owing to the observer’s subjectivity.