Achilles Tendon Resting Angle Relates to Tendon Length and Function

Zellers, Jennifer A.; Carmont, Michael R.; Silbernagel, Karin Grävare

doi:10.1177/1071100717742372

Cited by 55 publications

(76 citation statements)

References 24 publications

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“…[14][15][16][17] Similarly, tendon stiffness and slack length dictates the shortening demands of the plantarflexor muscles and impacts movement efficiency. 16,18,19 Resting ankle angle is often measured in clinical settings as surrogate measure of Achilles tendon slack length, 11,20 which is difficult to measure in vivo. While the effects of MTU parameters on walking biomechanics have been studied in great detail, 16,17,21,22 the multi-factorial implications of clinically-relevant MTU parameters on single-leg heel raise performance is poorly understood.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the purpose of this study was to characterize the sensitivity of single-leg heel raise height on plantarflexor MTU parameters. We hypothesized that optimal fiber length and resting ankle anglea clinical surrogate for tendon length 11,20 would have the greatest effect on singleleg heel raise performance. This hypothesis was supported by observations of shorter muscle fascicles, 5 longer tendons, 8 and less plantarflexed resting ankle angles 11 in patients who suffered Achilles tendon ruptures.…”

Section: Introductionmentioning

confidence: 99%

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Plantarflexor fiber length and tendon slack length are the strongest determinates of simulated single-leg heel raise function

Baxter

Farber

Hast

2018

Preprint

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Achilles tendon ruptures lead to reduced ankle function and often limits recreational activity. Single-leg heel raises are often used clinically to characterize patient function. However, it is unclear how the structure of the Achilles tendon and plantarflexor muscles affects single-leg heel raise function. Therefore, the purpose of this study was to develop a musculoskeletal model in order to simulate the effects of muscle-tendon unit (MTU) parameters on peak plantarflexion during this clinically-relevant task. The ankle joint was plantarflexed by two MTUs that represented the soleus and gastrocnemius muscles. The optimal fiber length, maximal muscle force, muscle pennation, tendon stiffness, and resting ankle anglea surrogate measure of tendon slack length were iteratively adjusted to test the combined effects of each of these MTU parameters. Singleleg heel raises were simulated by maximally exciting the two plantarflexor MTUs for each model configuration (N = 161,051 simulations). Optimal muscle fiber and tendon slack lengths had the greatest effect on peak plantarflexion during simulated single-leg heel raises. Simulations that were unable to produce at least 30 degrees of plantarflexion had muscle fibers that were shorter than healthy muscle and longer tendon slack lengths. These findings highlight the importance of preserving muscle fascicle and tendon length following Achilles tendon injuries.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plantarflexor fiber length and tendon slack length are the strongest determinates of simulated single-leg heel raise function

Baxter

Farber

Hast

2018

Preprint

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“…Deficits in plantarflexion function of the affected limb play a large role in preventing return to preinjury levels of activity (26) and have been shown to persist as far out as 14-years following injury (5,11). Clinically, these deficits present as decreased resting ankle angle (37), reduced calf-raise function (6,30), and 10-20% reductions in plantarflexion strength (11,21,27). Tendon elongation and plantarflexor muscle atrophy have both been associated with these reductions in function (10,23,30).…”

Section: Introductionmentioning

confidence: 99%

Gastrocnemius fascicles are shorter and more pennate throughout the first month following acute Achilles tendon rupture

Hullfish

O’Connor

Baxter

2018

Preprint

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1The purpose of this study was to characterize the short-term effects of Achilles tendon 2 ruptures on medial gastrocnemius. We hypothesized that the fascicles of the medial 3 gastrocnemius muscle of the injured Achilles tendon would be shorter and more pennate 4 immediately following the injury and would persist throughout 4 weeks post-injury. B-mode 5 longitudinal ultrasound images of the medial gastrocnemius were acquired in 10 adults who 6 suffered acute Achilles tendon ruptures and were treated non-operatively. Ultrasound images 7 were acquired during the initial clinical visit following injury as well as two and four weeks 8 following this initial clinical visit. Resting muscle structure was characterized by measuring 9 fascicle length, pennation angle, muscle thickness, and muscle echo intensity in both the injured 1 0 and contralateral (control) limbs. Fascicle length was 15% shorter (P < 0.001) and pennation 1 1 angle was 21% greater (P < 0.001) in the injured muscle compared to the uninjured (control) 1 2 muscle at the presentation of injury (week 0). These differences in fascicle length and pennation 1 3 angle persisted throughout the 4 weeks after the injury (P < 0.008). Muscle thickness changes 1 4were not detected at any of the post-injury visits (difference < 4%, P > 0.04). Echo intensity of 1 5 the injured limb was 8% lower at the presentation of the injury and 11% lower (P = 0.008) than 1 6 the contralateral muscle at 2 weeks following injury (P < 0.001) but returned to within 1% by 4 1 7 weeks (P = 0.393). Our results suggest that Achilles tendon ruptures elicit rapid changes in the

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“…We quantified resting 113 fascicle length, pennation angle, and muscle thickness with the ankle at the resting angle rather than at 114 neutral to avoid stretching the fascicles (Aeles et al, 2017). This resting angle was set to 16 degrees 115 plantar flexion for all subjects based on values of average resting ankle position across 42 patients 116 reported in the literature (Zellers et al, 2018). We manually 117 identified the superficial and deep aponeuroses and a 118 muscle fascicle by selecting two points on each structure to 119 form a line (Figure 1).…”

Section: Methods 95mentioning

confidence: 99%

Plantarflexor Torque and Work is Positively Correlated with Medial Gastrocnemius Fascicle Length in Healthy Young Adults

2019

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Running title. plantar flexor function correlates with fascicle length 13Word count. 3,455 14 Acknowledgements.We would like to thank R. Mathew and S. Donde for assistance with data 15 collection and processing. ABSTRACT 27Generating ankle torque is critical for locomotion in elite athletes, the elderly, and many patient 28 populations. Despite the robust findings linking plantar flexor muscle structure to gross function within 29 these populations, the link between variation in plantar flexor fascicle length and ankle kinetics in 30 healthy adults has not been established in the literature. In this study, we determined the relationship 31 between medial gastrocnemius structure and peak torque and total work produced by the plantar 32 flexors during maximal effort contractions. We measured resting fascicle length and pennation angle of 33 the medial gastrocnemius using ultrasound in healthy adult subjects (N=12). Subjects performed 34 maximal effort isometric and isokinetic contractions on a dynamometer. We found that longer fascicles 35 were positively correlated with higher peak torque and total work (R 2 > 0.41, p < 0.013) across all 36 isokinetic velocities, ranging from slow (30 degrees per second) to fast (210 degrees per second) 37contractions. Higher pennation angles were negatively correlated with peak torque and total work (R 2 > 38 0.296, p < 0.067). None of these correlations were significant in isometric conditions. To further 39investigate the coupled effect of fascicle length and pennation angle variation, we used a simple 40 computational model to simulate isokinetic contractions. These simulations confirmed that longer 41 fascicle lengths generate more joint torque and work throughout a greater range of motion. This study 42 provides experimental and computational evidence that links plantar flexor muscle structure and ankle 43 kinetics in healthy young adults, which lends new insight into locomotor function in a range of 44subpopulations. adults which provides insight into patient recovery following Achilles tendon rupture. 45

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Achilles Tendon Resting Angle Relates to Tendon Length and Function

Abstract: Level III, case-control study.

Cited by 55 publications

References 24 publications

Plantarflexor fiber length and tendon slack length are the strongest determinates of simulated single-leg heel raise function

Plantarflexor fiber length and tendon slack length are the strongest determinates of simulated single-leg heel raise function

Gastrocnemius fascicles are shorter and more pennate throughout the first month following acute Achilles tendon rupture

Plantarflexor Torque and Work is Positively Correlated with Medial Gastrocnemius Fascicle Length in Healthy Young Adults

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