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Reliability of Achilles Tendon Moment Arm Measured In Vivo Using Freehand Three-Dimensional Ultrasound

Steven J. Obst, Lee Barber, Ashton Miller, and Rod S. Barrett

Estimates of in vivo Achilles tendon (AT) force are needed to measure tendon mechanical properties as a function of the measured net ankle joint torque, and to understand AT function using musculoskeletal modeling approaches. The AT moment arm is required to convert the measured external ankle

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Achilles Tendon Properties of Minimalist and Traditionally Shod Runners

Katherine Histen, Julia Arntsen, Lauren L’Hereux, James Heeren, Benjamin Wicki, Sterling Saint, Giselle Aerni, Craig R. Denegar, and Michael F. Joseph


Tendon adapts to load through alterations in its composition and mechanical properties. Mechanical adaptation to increased load often involves increases in cross-sectional area (CSA), stiffness, and modulus. Runners exhibit these adaptations.


To determine if runners wearing minimalist shoes had larger and stiffer Achilles tendons (AT) than traditionally shod runners.


Cross-sectional study of well-trained, traditionally and minimally shod runners.


Laboratory assessment of trained runners.


23 men (11 traditional, 12 minimalist) and 8 women (6 traditional, 2 minimalist). Runners wearing minimalist shoes had 4.2 ± 1.6 y of training experience in minimalist shoes.

Main Outcome Measures:

The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force-elongation curve and its derivatives.


Minimalist runners had a greater CSA: mean difference (MD) = 9.2 mm2, stiffness (MD = 268.1 N/mm), and modulus (MD = 202.9 MPa). ATs of minimalist runners experienced greater stress (MD 8.6 N/mm2) during maximal voluntary isometric contraction of the plantar-flexor muscles due to greater force of contraction (MD 798.9 N).


The AT in minimalist runners adapts by increasing size, stiffness, and modulus, which is consistent with our understanding of mechanical adaptation of tendon to increased loading. Increased stress to the AT likely requires a slow transition to minimalist running to allow the AT to adapt without evidence of injury.

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An Algorithm for Automated Analysis of Ultrasound Images to Measure Tendon Excursion in Vivo

Sabrina S.M. Lee, Gregory S. Lewis, and Stephen J. Piazza

The accuracy of an algorithm for the automated tracking of tendon excursion from ultrasound images was tested in three experiments. Because the automated method could not be tested against direct measurements of tendon excursion in vivo, an indirect validation procedure was employed. In one experiment, a wire “phantom” was moved a known distance across the ultrasound probe and the automated tracking results were compared with the known distance. The excursion of the musculotendinous junction of the gastrocnemius during frontal and sagittal plane movement of the ankle was assessed in a single cadaver specimen both by manual tracking and with a cable extensometer sutured to the gastrocnemius muscle. A third experiment involved estimation of Achilles tendon excursion in vivo with both manual and automated tracking. Root mean squared (RMS) error was calculated between pairs of measurements after each test. Mean RMS errors of less than 1 mm were observed for the phantom experiments. For the in vitro experiment, mean RMS errors of 8–9% of the total tendon excursion were observed. Mean RMS errors of 6–8% of the total tendon excursion were found in vivo. The results indicate that the proposed algorithm accurately tracks Achilles tendon excursion, but further testing is necessary to determine its general applicability.

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The Use of Normalized Cross-Correlation Analysis for Automatic Tendon Excursion Measurement in Dynamic Ultrasound Imaging

Stephen J. Pearson, Tim Ritchings, and Ahmad S.A. Mohamed

The work describes an automated method of tracking dynamic ultrasound images using a normalized cross-correlation algorithm, applied to the patellar and gastrocnemius tendon. Displacement was examined during active and passive tendon excursions using B-mode ultrasonography. In the passive test where two regions of interest (2-ROI) were tracked, the automated tracking algorithm showed insignificant deviations from relative zero displacement for the knee (0.01 ± 0.04 mm) and ankle (–0.02 ± 0.04 mm) (P > .05). Similarly, when tracking 1-ROI the passive tests showed no significant differences (P > .05) between automatic and manual methods, 7.50 ± 0.60 vs 7.66 ± 0.63 mm for the patellar and 11.28 ± 1.36 vs 11.17 ± 1.35 mm for the gastrocnemius tests. The active tests gave no significant differences (P > .05) between automatic and manual methods with differences of 0.29 ± 0.04 mm for the patellar and 0.26 ± 0.01 mm for the gastrocnemius. This study showed that automatic tracking of in vivo displacement of tendon during dynamic excursion under load is possible and valid when compared with the standardized method. This approach will save time during analysis and enable discrete areas of the tendon to be examined.

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Nonuniform Deformation of the Patellar Tendon During Passive Knee Flexion

Laura C. Slane, Stijn Bogaerts, Darryl G. Thelen, and Lennart Scheys

Chronic tendon injuries, such as tendinopathy, commonly occur in energy-storing tendons and can have a high socioeconomic impact on the general population, both in terms of lost work and the effects on normal daily living. 1 Intriguingly, tendinopathies often arise in consistent locations

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Stress Relaxation and Targeted Nutrition to Treat Patellar Tendinopathy

Keith Baar

due to the high playing load and intensity. In a preliminary report from the Australian National Basketball League, 52.3% of players reported patellar tendon pain that limited performance ( Hannington et al., 2017 ), suggesting that the prevalence of this injury is high at the elite level. Typically

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The Effects of High-Load Slow-Velocity Resistance Exercise Training in Athletes With Tendinopathy: A Critically Appraised Topic

J. David Taylor, Annemieke Corbitt, and Ruth Ann Mathis

Clinical Scenario Tendinopathy is a relatively general term that describes a pathological state of a tendon. Possible characteristics of tendinopathy include inflammation, microtrauma, macrotrauma, tissue degeneration, and impaired response to mechanical loading. 1 Although the etiology is not

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Nutritional Supplements in the Clinical Management of Tendinopathy: A Scoping Review

Ian Burton and Aisling McCormack

Tendinopathy represents a spectrum of tendon pathology, associated with chronic tendon pain and impaired physical function, and as a disease entity is responsible for 30% to 5% of all musculoskeletal pathologies requiring medical treatment. 1 The worldwide increase in sports participation and

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The Effectiveness of Isometric Contractions Compared With Isotonic Contractions in Reducing Pain For In-Season Athletes With Patellar Tendinopathy

Chee Vang and Alexander Niznik

-inflammatories, injectable agents, phonophoresis, iontophoresis, orthotics, therapeutic ultrasound, and extracorporeal shockwave. 2 – 6 Exercise and tendon loading appear to demonstrate positive effects in histological changes and reduction in pain perception. Eccentric exercises have been widely utilized to treat patellar

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Utilizing A Percutaneous Versus Open Achilles Tendon Repair Technique for Treating Acute Achilles Tendon Ruptures in Physically Active Adults: A Critically Appraised Topic

Arhum Saleem, Irfan A. Khan, Nisha J. Crouser, and Kevin D. Martin

Clinical Scenario Despite being one of the strongest tendons in the body, Achilles tendon ruptures account for approximately 20% of all large tendon ruptures. 1 The incidence of Achilles tendon rupture has risen dramatically with the aging population, obesity, and increased participation in high