Reliability and validity of the measurement of position sense in women with osteoarthritis of the knee.

Abstract

We examined the test-retest reliability and the construct validity of the measurement of knee position sense for describing the functional weightbearing performance of women with osteoarthritis (OA) of the knee. For the purpose of this study, position sense was defined as the error occurring when subjects attempted to reproduce a criterion angle in standing with visual cues eliminated. Five such tests were recorded photographically on 3 different occasions. On each occasion the 10 subjects also completed a self-paced walking test over a 13 m indoor walkway. The photographic measurements were reproducible (r = 0.90) and there was no change in positioning accuracy across sessions. There was a significant (p < 0.05) inverse correlation of 0.70 between the standard deviation of the mean individual measurements of position sense (precision of the test) and those of walking speed. Our study demonstrates good measurement reliability and a comparable mean angular error with repeated tests. It also suggests the amplitude of the variability of this error is a strong determinant of an individual OA patient's functional performance in walking.