Ankle Joint Position and the Reliability of Ultrasound Tissue Characterization of the Achilles Tendon: A Pilot Study

Abstract

BackgroundImaging of the Achilles tendon using ultrasound tissue characterization (UTC) involves taking up the slack of the tendon by including dorsiflexion of the ankle. This pilot study aimed to determine whether different longitudinal tension applied to the Achilles tendon during imaging affected the reliability of UTC.Material/MethodsNine asymptomatic active volunteers, aged between 23–49 years underwent imaging of 17 Achilles tendons. Three positions of tension included plantar grade, 50%, and 100% of maximal dorsiflexion, with a range of 18–32°. Ranges were established and standardized using an isokinetic dynamometer. A test and re-test process was conducted at each position to determine the intraclass correlation coefficients (ICCs) and minimum detectable change (MDC) per echotype. Images were analyzed using UTC software.ResultsPlantar grade positioning images could not be obtained. ICCs for each echotype I–IV between test 1 and test 2 were 0.965, 0.962, 0.858, 0.739 at 100% dorsiflexion (95% CI, 0.86–0.99, 0.84–0.99, 0.51–0.97, and 0.2–0.94), and 0.771, 0.551, 0.569, 0.429 at 50% dorsiflexion (95% CI, 0.29–0.94, −0.09–0.88, −0.01–0.88, and −0.15–0.82). The MDC per echotype I–IV ranged between 4.1–1.0% of echotype data at 100% dorsiflexion, and 17.2–6.3% at 50% dorsiflexion.ConclusionsTesting at maximum dorsiflexion provided improved reliability when using UTC in healthy individuals. The ICC at 100% dorsiflexion was increased, and the MDC was reduced for all echotypes. Therefore, standardizing test positions when using UTC is advisable for reliable comparison of results between studies.

Achilles Scraping and Plantaris Tendon Removal Improves Pain and Tendon Structure in Patients with Mid-Portion Achilles Tendinopathy—A 24 Month Follow-Up Case Series

“…Individual VISA-A responses can be viewed in Figure 2 . The structure of the Achilles mid-portion improved, with organised echo pixels (UTC type I + II) increasing from 79.9 (±11.5) to 86.4 (±10.0) (mean difference 6.5%, 95% CI = −0.80–13.80, p = 0.01), exceeding the 3.4% minimum detectable change [ 30 ] (see Table 2 and Figure 3 ).…”

“…In a previous study, decreased tendon thickness and improved structure verified by grey-scale ultrasound were reported after successful sclerosing polidocanol injection treatment in patients with chronic painful midportion Achilles tendinopathy [ 33 ]. In the current study UTC was used, which is a more reliable and objective method to analyse changes in tendon structure [ 30 ].…”

“…The echo structure of the tendon was quantified from the insertion to the soleus musculotendinous junction and expressed as a percentage of tendon volume. This method has previously been reported to be reliable and have a minimal detectable difference of 3.4% [ 30 ].…”