Monitoring in-shoe plantar pressures, temperature, and humidity: reliability and validity of measures from a portable device.
OBJECTIVE
To investigate the reliability and validity of measures obtained from a portable electronic device used to monitor changes in plantar pressure, temperature, and humidity that occur within the shoe during prolonged activity.


METHODS
Descriptive study comparing electronic sensor output with criterion values.


METHODS
Indoor level walkway for pressure data; uncontrolled, outdoor environment for step count data; enclosed environmental control chamber for humidity and temperature data.


METHODS
Convenience sample of 4 healthy, sensate subjects.


METHODS
Not applicable.


METHODS
Correlations between sensor output and criterion measures were determined for pressure and temperature data. The absolute differences between sensor output and criterion values of temperature, humidity, and step count were also determined.


RESULTS
Pressure measurements from electronic sensors correlated highly with criterion values (r > or =.82), both before and after prolonged use. Relative humidity sensor output were within 5% of hygrometer values. In-shoe temperature data correlated highly with criterion values (r > or =.99), and differed from known temperatures by.50 degrees +/-.84 degrees C and.96 degrees +/- 1.56 degrees C at the forefoot and heel, respectively. Electronic step counts recorded at the central forefoot were within 1 step of visual step counts. Pressure tracings obtained from the device during different weight-bearing activities revealed qualitatively distinct pressure patterns.


CONCLUSIONS
The device provides valid and reliable measures of in-shoe plantar pressures, temperature, and humidity during prolonged activity.
Maluf
K S
KS
Program in Physical Therapy, Washington University School of Medicine, St. Louis, MO 63108-2212, USA.
Morley
R E
RE
Richter
E J
EJ
Klaesner
J W
JW
Mueller
M J
MJ
D017719:Diabetic Foot / Q000517:prevention & control*; D004581:Electronics; D004867:Equipment Design; D006801:Humans; D006813:Humidity; D009989:Orthotic Devices; D011312:Pressure; D015203:Reproducibility of Results; D012775:Shoes; D013696:Temperature