Ultrasonography for the assessment of the structural properties of the Achilles tendon in asymptomatic individuals: An intra-rater reproducibility study
Affiliations: [a] University Outpatient Clinic, Sports Medicine and Sports Orthopaedics, University of Potsdam, Potsdam, Germany | [b] Department of Health Science and Technology, Institute for Biomechanics, ETH Zürich, Zürich, Switzerland
Correspondence:
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Corresponding author: Konstantina Intziegianni, University Outpatient Clinic, Sports Medicine and Sports Orthopaedics, University of Potsdam, Am Neuen Palais 10, Haus 12, 14469 Potsdam, Germany. Tel.: +49 331 9771640; Fax: +49 331 9771296; E-mail:intziegi@uni-potsdam.de
Abstract:
BACKGROUND: Reproducible measurements of tendon structural
properties are a prerequisite for accurate diagnosis of tendon disorders and
for determination of their mechanical properties. Despite the widely used
application of Ultrasonography (US) in musculoskeletal assessment, its
operator dependency and lack of standardization influences the consistency
of the measurement. OBJECTIVE: To evaluate the intra-rater reproducibility of a
standardized US method assessing the structural properties of the Achilles
tendon (AT). METHODS: Sixteen asymptomatic participants were positioned
prone on an isokinetic dynamometer with the knee extended and ankle at
90° flexion. US was used to assess AT-length, cross-sectional area
(CSA), and AT-elongation during isometric plantarflexion contraction. The
intra-rater reproducibility was assessed by ICC (2.1), Test-Retest
Variability (TRV, %), Bland-Altman analyses (Bias ± LoA [1.96*SD]), and
Standard-Error of Measurement (SEM). RESULTS: Measurements of AT-length demonstrated an ICC of 0.93, TRV
of 4.5 ± 3.9%, Bias ± LoA of -2.8 ± 25.0 mm and SEM of 6.6 mm.
AT-CSA showed an ICC of 0.79, TRV of 8.7 ± 9.6%, Bias ± LoA of
1.7 ± 19.4 mm2 and SEM of 5.3 mm2. AT-elongation revealed an
ICC of 0.92, TRV of 12.9 ± 8.9%, Bias ± LoA of 0.3 ± 5.7 mm and
SEM of 1.5 mm. CONCLUSIONS: The presented methodology allows a reproducible
assessment of Achilles tendon structural properties when performed by a
single rater.
