Ultrasonographic measurement of patellar tendon thickness--a study of intra- and interobserver reliability.

This article determines intra- and intertester reliability and measurement precision of ultrasonographic assessment of patellar tendon (PT) thickness. Eighteen healthy subjects were scanned three times in two sessions with a 45-min interval by two experienced examiners. Reliability and measurement precision were evaluated using intraclass correlation coefficient and limits of agreement. When measuring PT thickness, a mean of two measurements is recommended, and changes larger than 0.07 cm can be considered actual changes and not a result of measurement uncertainty.