Generalizability of in-shoe peak pressure measures using the F-scan system

In-shoe pressure analysis can be useful in the management of a variety of foot and ankle problems, but guidelines are needed to determine the practical limitations of the measures. The primary purpose of this study was to determine the reliability of peak plantar pressures taken with the F-Scan system over multiple steps, sensors, and days, and using a force platform for additional calibration. Data were collected on 10 healthy subjects as they walked across a force platform for a minimum of three trials on four separate sessions that were 1 week apart. Using a mean of three steps with a single sensor on 1 day, generalizability coefficients were 0.75 for manufacturer calibration and 0.82 with force platform calibration; reliability coefficients for absolute decisions (index of dependability) were 0.60 for manufacturer calibration and 0.76 with force platform calibration. Force measures from the F-Scan and force platform were highly correlated (r = 0.93), but the absolute difference between the measures varied between sensors and over time. Relevance-Peak pressure measures taken from a mean of three steps with procedures outlined by the F-Scan manufacturer provide pressure values that demonstrate adequate reliability for clinical and research purposes when rank ordering of measures is indicated, If measures are to be used for making absolute decisions (e.g., identifying a threshold for injury), calibration from a stable source such as a force platform is recommended.