Ultrasound (US) assessments of the Achilles tendon are commonly used in clinical settings to differentiate between tendons with several pathologies such as tendinopathy, partial tear, complete tear, calcifications, etc. US technology is also being used in clinical and/or research settings, where measurements of Achilles tendon size are used to assess the tendon's response to exercise, aging, rehabilitation, tendon loading and healing.
Good to excellent reliability can be achieved by non-US specialists for US measurements of the cross-sectional area, depth and width of the Achilles tendon at various tendon sites; however, overall, there was a high risk of methodological bias across the included studies. Reliability can be optimized by using one experienced operator, standardizing transducer pressure and transducer orientation and averaging two or three measurements. Reliability of measurements made at the distal and proximal ends of the tendon may be compromised by the loss of image clarity of the Achilles tendon caused by oblique tendon fibers > Silbernagel et al. 2016; Thoirs et al. 2018