Comparison of Kistler 9861A force platform and Chattecx Balance System for measurement of postural sway: correlation and test-retest reliability

Abstract

Measurement of postural sway has several potential applications in sports medicine. Traditionally, however, rather complicated equipment has been applied. The purpose of the study was to compare two devices based on two different methods of measuring postural sway: (i) a sophisticated Kistler 9861A force platform (KIS)--which all but requires a laboratory setting--and (ii) Chattecx Balance System (CBS)--which is particularly suited for measurement of sway in the dynamic environment of sports. Measurement of sway was performed in 29 subjects twice at baseline and twice at follow-up 2-4 weeks later. One measurement consisted of four 25-second sequences (eyes open, parallel feet; eyes closed, parallel feet; eyes open, tandem Romberg; eyes closed, tandem Romberg). Factor analysis revealed influence of sight and stance on sway, marked interaction between these two factors and a decrease in sway on retest on the same day. Coefficients of variation were--KIS: 0.13-0.23; CBS: 0.11-0.25. Body height was a covariate for all parameters. Kistler 9861A force platform and CBS were correlated (baseline: r(s) = 0.47; follow-up: r(s) = 0.9). These findings suggest that, when the effects of acclimatization and covariance of body height were taken into account, CBS was as reliable and reproducible as KIS in our laboratory.