| Summary: | This study investigated the reproducibility of test results of the Langer Electrodynogram (EDG) foot sensor system which quantifies discrete pressures and temporal episodes at the interface of the foot and appropriate surface. In phase one of the study, the effects of transducer placement errors were evaluated by manipulating sensors. In the single subject studied, results suggested that placement errors of a single transducer within ${ pm1}$ cm from its original location do not significantly affect the temporal components of gait, though errors as low as ${ pm0.5}$ cm from an initial position significantly affected pressures. === In phase two, ten healthy subjects performed 25 straight line barefoot walks on each of two separate days at an average natural cadence of 111.06 steps/min. with identical transducer placements on each day. Twenty-five gait variables were analysed for unilateral and asymmetries estimates. Analyses of variance revealed few significant differences among trials. Further, while there were no significant overall differences between days, there were significant subject-by-day interactions due to between-day differences in individual subjects, in part related to inherent subject-performance variability. Since clinicians are interested mainly in individual subject analyses rather than a mythical average subject, caution is advised in data interpretation when monitoring a subject on different days, even with as many as 25 trials per session and identical landmark placements. Pressures, while reliable within a single testing session, should not be used for inter-day comparisons and may not be appropriate for monitoring asymmetries because slight variations in placement will account for the measured differences between limbs.
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