Tendon morphology and mechanical properties assessed by ultrasound show change early in recovery and potential prognostic ability for 6-month outcomes

  • Jennifer A. Zellers
  • Daniel H. Cortes
  • Ryan T. Pohlig
  • Karin Grävare SilbernagelEmail author



Optimizing tendon structural recovery during the first 12 weeks after Achilles tendon rupture is a prime target to improve patient outcomes, but a comprehensive understanding of biomarkers is needed to track early healing. The purpose of this study was to observe healing of tendon structure over time using ultrasound-based, tendon-specific measures and to identify relationships between tendon structural characteristics and clinical measures of gait and strength.


Twenty-seven participants (21 males, mean (SD) age 39 (11) years) were assessed at 4, 8, 12, and 24 weeks after injury or surgery using ultrasound imaging techniques. Gait analysis and strength testing were added at the later time points.


Ruptured tendons had significantly lower dynamic shear modulus (p < 0.001), greater tendon cross-sectional area (p < 0.001), and greater length (p < 0.001) than the uninjured side. Dynamic shear modulus, cross-sectional area, and length were found to increase over time (p < 0.01). Tendon structure at 4 weeks post-injury [cross-sectional area symmetry (r = 0.737, p = 0.002) and dynamic shear modulus (r = 0.518, p = 0.040)] related to stance phase walking symmetry at 24 weeks.


Tendon structure assessed by ultrasound imaging changes over the first 24 weeks of healing after Achilles tendon rupture, suggesting it could be used as a biomarker to track tendon healing early in recovery. Additionally, tendon structure within the first 12 weeks relates to later walking gait and heel-rise symmetry, which may indicate that tendon structure could have prognostic value in the care of these patients. This study’s clinical relevance is in its support for using ultrasound imaging to assess early patient healing and prognosticate later patient outcomes after Achilles tendon rupture.

Level of evidence

Level 2, prospective cohort prognostic study.


Ultrasound Elastography Outcomes Ankle 



This study was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award number R21AR067390 and the National Institutes of Health under Award number P30-GM103333. This study was also funded by the Foundation for Physical Therapy and the University of Delaware Research Foundation. The study sponsors did not play a role in the study design, collection, analysis, interpretation of data, or the writing/submission of this manuscript for publication. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.


This study was funded by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health (R21AR067390), the National Institutes of Health (P30-GM103333), the Foundation for Physical Therapy and the University of Delaware Research Foundation.

Compliance with ethical standards

Conflict of interest

The authors have no additional conflict of interest.

Ethical approval

Ethical approval was obtained from the University of Delaware Institutional Review Board (784188-1).

Informed consent

All participants provided written informed consent prior to participation.


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Copyright information

© European Society of Sports Traumatology, Knee Surgery, Arthroscopy (ESSKA) 2018

Authors and Affiliations

  • Jennifer A. Zellers
    • 1
  • Daniel H. Cortes
    • 2
  • Ryan T. Pohlig
    • 3
  • Karin Grävare Silbernagel
    • 1
    Email author
  1. 1.Department of Physical TherapyUniversity of DelawareNewarkUSA
  2. 2.Department of Mechanical and Nuclear EngineeringPenn State UniversityState CollegeUSA
  3. 3.College of Health Sciences Biostatistics Core FacilityUniversity of DelawareNewarkUSA

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