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Influence of anatomical geometry and fiber dispersion on Achilles tendon Mechanics : A finite element modelling approach

Pydi, Yeswanth S. LU ; Pierantoni, Maria LU orcid ; Gustafsson, Anna LU orcid and Isaksson, Hanna LU orcid (2026) In Journal of Biomechanics 204.
Abstract

Tendons adapt their structure and mechanical behavior in response to mechanical loading, where mechanical stimuli, such as strain, are believed to play a pivotal role. Recent studies employing finite element modeling have provided detailed insights into the distribution of strain across tendon structures under various loading conditions. However, most researchers have adopted highly simplified geometries, which are unable to capture the inherent strain heterogeneity in tendons, thereby emphasizing the need for anatomically accurate models. The current study explores how both geometry and fiber orientation impact tendon strain heterogeneity using anatomically detailed finite element models of rat Achilles tendons. To achieve this,... (More)

Tendons adapt their structure and mechanical behavior in response to mechanical loading, where mechanical stimuli, such as strain, are believed to play a pivotal role. Recent studies employing finite element modeling have provided detailed insights into the distribution of strain across tendon structures under various loading conditions. However, most researchers have adopted highly simplified geometries, which are unable to capture the inherent strain heterogeneity in tendons, thereby emphasizing the need for anatomically accurate models. The current study explores how both geometry and fiber orientation impact tendon strain heterogeneity using anatomically detailed finite element models of rat Achilles tendons. To achieve this, phase-contrast enhanced synchrotron X-ray tomography images were used to obtain the tendon geometry and fiber orientation. Two different types of geometrical models, based on anatomical segmentation and simplified cylindrical with straight fiber distribution, were analyzed to understand the effect of geometry under cyclic loads. The force time responses, maximum principal strain distributions, and fluid velocities were analyzed to understand the effect of geometry. Similar parameters were analyzed for the anatomical model using straight fibers and dispersed fibers using both the average global and locally mapped fiber distribution to understand the effect of fiber orientation and dispersion. The results reveal that geometry and fiber orientation significantly affect the tendon's mechanical behavior. The anatomical models resulted in greater strain heterogeneity, with maximum principal strain varying from (0.070 ± 0.020) compared to the cylindrical model (0.058 ± 0.015), and including the dispersed fiber orientation (global and local) increased the velocity of the fluid pushed out from the tendon during loading. This may have implications for mechanobiological predictions of tendon function.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
3D fiber orientation analysis, Anatomical tendon model, Fiber-reinforced model, Finite element analysis, Poro-elasticity
in
Journal of Biomechanics
volume
204
article number
113358
publisher
Elsevier
external identifiers
  • pmid:42134257
  • scopus:105038921502
ISSN
0021-9290
DOI
10.1016/j.jbiomech.2026.113358
language
English
LU publication?
yes
id
336ca8a2-7bc1-4a9e-b82d-ca64c740ceb9
date added to LUP
2026-07-10 13:16:23
date last changed
2026-09-04 18:18:23
@article{336ca8a2-7bc1-4a9e-b82d-ca64c740ceb9,
  abstract     = {{<p>Tendons adapt their structure and mechanical behavior in response to mechanical loading, where mechanical stimuli, such as strain, are believed to play a pivotal role. Recent studies employing finite element modeling have provided detailed insights into the distribution of strain across tendon structures under various loading conditions. However, most researchers have adopted highly simplified geometries, which are unable to capture the inherent strain heterogeneity in tendons, thereby emphasizing the need for anatomically accurate models. The current study explores how both geometry and fiber orientation impact tendon strain heterogeneity using anatomically detailed finite element models of rat Achilles tendons. To achieve this, phase-contrast enhanced synchrotron X-ray tomography images were used to obtain the tendon geometry and fiber orientation. Two different types of geometrical models, based on anatomical segmentation and simplified cylindrical with straight fiber distribution, were analyzed to understand the effect of geometry under cyclic loads. The force time responses, maximum principal strain distributions, and fluid velocities were analyzed to understand the effect of geometry. Similar parameters were analyzed for the anatomical model using straight fibers and dispersed fibers using both the average global and locally mapped fiber distribution to understand the effect of fiber orientation and dispersion. The results reveal that geometry and fiber orientation significantly affect the tendon's mechanical behavior. The anatomical models resulted in greater strain heterogeneity, with maximum principal strain varying from (0.070 ± 0.020) compared to the cylindrical model (0.058 ± 0.015), and including the dispersed fiber orientation (global and local) increased the velocity of the fluid pushed out from the tendon during loading. This may have implications for mechanobiological predictions of tendon function.</p>}},
  author       = {{Pydi, Yeswanth S. and Pierantoni, Maria and Gustafsson, Anna and Isaksson, Hanna}},
  issn         = {{0021-9290}},
  keywords     = {{3D fiber orientation analysis; Anatomical tendon model; Fiber-reinforced model; Finite element analysis; Poro-elasticity}},
  language     = {{eng}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Biomechanics}},
  title        = {{Influence of anatomical geometry and fiber dispersion on Achilles tendon Mechanics : A finite element modelling approach}},
  url          = {{http://dx.doi.org/10.1016/j.jbiomech.2026.113358}},
  doi          = {{10.1016/j.jbiomech.2026.113358}},
  volume       = {{204}},
  year         = {{2026}},
}