Quantifying Achilles tendon force in vivo from ultrasound images

Magnitude of the reflex contribution to force enhancement was investigated in vivo during passive stretches of the Achilles tendon (AT) of one female subject. Thirty passive (5 × 6) dorsiflexions were induced by a motorized ankle ergometer. Achilles tendon force (ATF) was sensed by a buckle transducer applied surgically around the right AT. Single passive stretches resulted in a low but rather linear ATF increase in the absence of EMG (surface electrodes) activity. In the presence of reflexes, a clear ATF enhancement occurred 13–15 ms after the beginning of the EMG reflex responses. In double dorsiflexions at either 1.2 or 1.9 rad · s-1, which were separated by a maintained stretched position of either 40 or 90 ms, the first stretch resulted in initial linear ATF increase, followed by an additional force enhancement during the plateau phase. This reflexly induced increase represented 94 ± 4 N and 184 ± 1 N, respectively, for the 40 and the 90 ms plateaus, corresponding to 210 ± 85% and 486 ± 177% enhancements as compared to the first passive stretch effect. The results suggest further that timing of the stretch during the twitch response influences the magnitude and rate of force potentiation.

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

Journal of Applied Biomechanics ◽

10.1123/jab.24.1.75 ◽

2008 ◽

Vol 24 (1) ◽

pp. 75-82 ◽

Cited By ~ 21

Author(s):

Sabrina S.M. Lee ◽

Gregory S. Lewis ◽

Stephen J. Piazza

Keyword(s):

Achilles Tendon ◽

Sagittal Plane ◽

Ultrasound Images ◽

General Applicability ◽

Musculotendinous Junction ◽

Automated Tracking ◽

Automated Method ◽

Tendon Excursion ◽

Rms Errors

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 Effects of Orthotic Heel Lifts on Achilles Tendon Force and Strain During Running

Journal of Applied Biomechanics ◽

10.1123/jab.28.5.511 ◽

2012 ◽

Vol 28 (5) ◽

pp. 511-519 ◽

Cited By ~ 15

Author(s):

Dominic James Farris ◽

Erica Buckeridge ◽

Grant Trewartha ◽

Miranda Polly McGuigan

Keyword(s):

Achilles Tendon ◽

Lower Limb ◽

Inverse Dynamics ◽

Force Plate ◽

Medial Gastrocnemius ◽

Ultrasound Images ◽

Moment Arm ◽

Flexion Extension ◽

Tendon Force ◽

The Right

This study assessed the effects of orthotic heel lifts on Achilles tendon (AT) force and strain during running. Ten females ran barefoot over a force plate in three conditions: no heel lifts (NHL), with 12 mm heel lifts (12HL) and with 18 mm heel lifts (18HL). Kinematics for the right lower limb were collected (200 Hz). AT force was calculated from inverse dynamics. AT strain was determined from kinematics and ultrasound images of medial gastrocnemius (50 Hz). Peak AT strain was less for 18HL (5.5 ± 4.4%) than for NHL (7.4 ± 4.2%) (p = .029, effect size [ES] = 0.44) but not for 12HL (5.8 ± 4.8%) versus NHL (ES = 0.35). Peak AT force was significantly (p = .024, ES = 0.42) less for 18HL (2382 ± 717 N) than for NHL (2710 ± 830 N) but not for 12HL (2538 ± 823 N, ES = 0.21). The 18HL reduced ankle dorsiflexion but not flexion-extension ankle moments and increased the AT moment arm compared with NHL. Thus, 18HL reduced force and strain on the AT during running via a reduction in dorsiflexion, which lengthened the AT moment arm. Therefore, heel lifts could be used to reduce AT loading and strain during the rehabilitation of AT injuries.

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

Journal of Applied Biomechanics ◽

10.1123/jab.2016-0261 ◽

2017 ◽

Vol 33 (4) ◽

pp. 300-304 ◽

Cited By ~ 9

Author(s):

Steven J. Obst ◽

Lee Barber ◽

Ashton Miller ◽

Rod S. Barrett

Keyword(s):

Achilles Tendon ◽

Plantar Flexion ◽

Three Dimensional ◽

Correlation Coefficients ◽

Lateral Malleolus ◽

Medial Malleolus ◽

Minimal Detectable Change ◽

Ultrasound Images ◽

Moment Arm

This study investigated reliability of freehand three-dimensional ultrasound (3DUS) measurement of in vivo human Achilles tendon (AT) moment arm. Sixteen healthy adults were scanned on 2 separate occasions by a single investigator. 3DUS scans were performed over the free AT, medial malleolus, and lateral malleolus with the ankle passively positioned in maximal dorsiflexion, mid dorsiflexion, neutral, mid plantar flexion and maximal plantar flexion. 3D reconstructions of the AT, medial malleolus, and lateral malleolus were created from manual segmentation of the ultrasound images and used to geometrically determine the AT moment arm using both a straight (straight ATMA) and curved (curved ATMA) tendon line-of-action. Both methods were reliable within- and between-session (intra-class correlation coefficients > 0.92; coefficient of variation < 2.5 %) and revealed that AT moment arm increased by ∼ 7 mm from maximal dorsiflexion (∼ 41mm) to maximal plantar flexion (∼ 48 mm). Failing to account for tendon curvature led to a small overestimation (< 2 mm) of AT moment arm that was most pronounced in ankle plantar flexion, but was less than the minimal detectable change of the method and could be disregarded.

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Individual muscle contributions to the in vivo achilles tendon force

Clinical Biomechanics ◽

10.1016/s0268-0033(98)00032-1 ◽

1998 ◽

Vol 13 (7) ◽

pp. 532-541 ◽

Cited By ~ 105

Author(s):

A.N. Arndt ◽

P.V. Komi ◽

G.-P. Brüggemann ◽

J. Lukkariniemi

Keyword(s):

Achilles Tendon ◽

Individual Muscle ◽

Tendon Force

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Three-dimensional deformation and transverse rotation of the human free Achilles tendon in vivo during isometric plantarflexion contraction

Journal of Applied Physiology ◽

10.1152/japplphysiol.01249.2013 ◽

2014 ◽

Vol 116 (4) ◽

pp. 376-384 ◽

Cited By ~ 29

Author(s):

Steven J. Obst ◽

Jean-Baptiste Renault ◽

Richard Newsham-West ◽

Rod S. Barrett

Keyword(s):

Achilles Tendon ◽

Three Dimensional ◽

Tendon Injury ◽

Ultrasound Images ◽

Maximal Voluntary Isometric Contraction ◽

Cross Sectional ◽

Tendon Length ◽

Transverse Rotation ◽

Transverse Strains

Freehand three-dimensional ultrasound (3DUS) was used to investigate longitudinal and biaxial transverse deformation and rotation of the free Achilles tendon in vivo during a voluntary submaximal isometric muscle contraction. Participants ( n = 8) were scanned at rest and during a 70% maximal voluntary isometric contraction (MVIC) of the plantarflexors. Ultrasound images were manually digitized to render a 3D reconstruction of the free Achilles tendon for the computation of tendon length, volume, cross-sectional area (CSA), mediolateral diameter (MLD), anteroposterior diameter (APD), and transverse rotation. Tendon longitudinal and transverse (CSA, APD, and MLD) deformation and strain at 70% MVIC were calculated relative to the resting condition. There was a significant main effect of contraction on tendon length and mean CSA, MLD, and APD ( P < 0.05), but no effect on tendon volume ( P = 0.70). Group mean transverse strains for CSA, MLD, and APD averaged over the length of the tendon were −5.5%, −8.7% and 8.7%, respectively. Peak CSA, MLD, and APD transverse strains all occurred between 40% and 60% of tendon length. Transverse rotation of the free tendon was negligible at rest but increased under load, becoming externally rotated relative to the calcaneal insertion. The relationship between longitudinal and transverse strains of the free Achilles tendon during muscle-induced elongation may be indicative of interfascicle reorganization. The finding that transverse rotation and strain peaked in midportion of the free Achilles tendon may have important implications for tendon injury mechanisms and estimation of tendon stress in vivo.

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Development of a semi-automated segmentation tool for high frequency ultrasound image analysis of mouse echocardiograms

Scientific Reports ◽

10.1038/s41598-021-85971-3 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kristi Powers ◽

Raymond Chang ◽

Justin Torello ◽

Rhonda Silva ◽

Yannick Cadoret ◽

...

Keyword(s):

Image Analysis ◽

Automated Analysis ◽

Structure And Function ◽

Ultrasound Images ◽

Cardiac Structure ◽

Short Axis ◽

Pixel Intensity ◽

Cardiac Structure And Function ◽

And Function

AbstractEchocardiography is a widely used and clinically translatable imaging modality for the evaluation of cardiac structure and function in preclinical drug discovery and development. Echocardiograms are among the first in vivo diagnostic tools utilized to evaluate the heart due to its relatively low cost, high throughput acquisition, and non-invasive nature; however lengthy manual image analysis, intra- and inter-operator variability, and subjective image analysis presents a challenge for reproducible data generation in preclinical research. To combat the image-processing bottleneck and address both variability and reproducibly challenges, we developed a semi-automated analysis algorithm workflow to analyze long- and short-axis murine left ventricle (LV) ultrasound images. The long-axis B-mode algorithm executes a script protocol that is trained using a reference library of 322 manually segmented LV ultrasound images. The short-axis script was engineered to analyze M-mode ultrasound images in a semi-automated fashion using a pixel intensity evaluation approach, allowing analysts to place two seed-points to triangulate the local maxima of LV wall boundary annotations. Blinded operator evaluation of the semi-automated analysis tool was performed and compared to the current manual segmentation methodology for testing inter- and intra-operator reproducibility at baseline and after a pharmacologic challenge. Comparisons between manual and semi-automatic derivation of LV ejection fraction resulted in a relative difference of 1% for long-axis (B-mode) images and 2.7% for short-axis (M-mode) images. Our semi-automatic workflow approach reduces image analysis time and subjective bias, as well as decreases inter- and intra-operator variability, thereby enhancing throughput and improving data quality for pre-clinical in vivo studies that incorporate cardiac structure and function endpoints.

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