Reliability and accuracy of biomechanical measurements of the lower extremities.

The reliability of biomechanical measurements of the lower extremities, as they are commonly used in podiatric practice, was quantified by means of intraclass correlation coefficients (ICCs). This was done not only to evaluate interrater and intrarater reliability but also to provide an estimate for the accuracy of the measurements. The measurement protocol involved 30 asymptomatic subjects and five raters of varying experience. Each subject was measured twice by the same rater, with the retest immediately following the test. The study demonstrated that the interrater ICCs were quite low (< or =0.51), except for the measurements of relaxed calcaneal stance position and forefoot varus (both 0.61 and 0.62 for left and right, respectively). However, the intrarater ICCs were relatively high (>0.8) for most raters and measurement variables. Measurement accuracy was moderate between raters.