Are Ultrasound Measurements of Achilles Tendon Size Reliable? A Systematic Review of Rater Reliability.

Ultrasound measurements of Achilles tendon size are used to assess the tendon's response to exercise, aging, rehabilitation, tendon loading and healing. It is important to understand and minimise the measurement error that occurs with these measurements. This review identified and synthesised studies reporting on intra- and inter-rater reliability of ultrasound measurements of Achilles tendon size. Analysis of 21 studies revealed that good to excellent intra- and inter-rater reliability can be achieved for ultrasound measurements of Achilles tendon size. Reliability can be optimised by using one experienced operator, standardising transducer pressure and orientation and averaging two or three measurements. There was a high risk of methodological bias across the included studies. Reporting of reliability studies needs to be improved by the use of existing reporting guidelines and expansion of these guidelines to include important elements of ultrasound imaging.