Individual variation in Achilles tendon morphology and geometry changes susceptibility to injury

  1. Nai-Hao Yin
  2. Paul Fromme
  3. Ian McCarthy
  4. Helen L Birch  Is a corresponding author
  1. Research Department of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, United Kingdom
  2. Department of Mechanical Engineering, University College London, United Kingdom
  3. Pedestrian Accessibility and Movement Environment Laboratory, Department of Civil, Environmental and Geomatic Engineering, University College London, United Kingdom
7 figures, 1 table and 2 additional files

Figures

Three-dimensional computer models of Achilles sub-tendons.
Figure 2 with 1 supplement
Mean displacement of the proximal soleus face of three models with different friction contacts when each sub-tendon was loaded in isolation.
Figure 2—figure supplement 1
Mean transverse plane displacements (in mm) of the proximal soleus face of the three models with different friction contacts (x-axes) when each sub-tendon was loaded in isolation.

Large variations in displacements and directions were noted between different models under different loading conditions. The scale of the y-axes differs to allow better visualisation of differences in the data.

Normalised (to frictionless, coefficient = 0) proximal soleus face displacement of different friction contacts when each sub-tendon was loaded in isolation.

Note the scale of the y-axes differs to allow better visualisation of differences in the data.

Mean normalised (upper row) and peak (lower row) von Mises stress of the whole Achilles tendon for different friction coefficients when each sub-tendon was loaded in isolation.

Note the scale of the y-axes differs to allow better visualisation of differences in the data.

Change in peak stress location when shifting from frictionless (upper row) to frictional (lower row) contact is structure dependent.

LG: lateral gastrocnemius, MG: medial gastrocnemius, S: soleus sub-tendon. View planes: Ant.: anterior, Pos.: posterior, Lat.: lateral, Med.: medial, Int.: internal view with the covering sub-tendon removed.

Group differences in normalised soleus junction displacement during different stimulation trials.
Simplified sagittal plane view of triceps surae muscle-tendon units and corresponding ultrasound measurement locations (left) and sequences of measurement during each stimulation trial (right).

MG/LG: medial or lateral gastrocnemius, SOL: soleus. MTJ: musculotendinous junction.

Tables

Table 1
Mechanical testing results of three Achilles sub-tendons.
SpecimenCSA (mm2)Failure force (N)Ultimate stress (MPa)Ultimate strain (%)Young’s modulus (MPa)Stiffness (N/mm)
(age–sex)LGMGSLGMGSLGMGSLGMGSLGMGSLGMGS
69 M13.614.539.2325.0402.21701.224.027.745.39.710.019.1353.9375.8399.479.997.6260.6
78 F12.410.820.6154.7571.11155.612.552.656.211.68.917.5175.0771.1421.136.7145.6167.8
84 F5.710.730.9503.6621.81577.089.058.351.08.912.210.41231.5636.9734.9118.2121.4385.1
85 F10.414.038.2787.5688.31090.975.849.028.611.910.615.8853.6617.2239.9151.7144.7156.6
87 M4.617.035.2301.6647.71578.565.938.144.98.210.210.81033.4496.2606.280.9143.0349.6
Mean9.3*13.4*32.8414.5*586.2*1420.653.445.145.210.110.414.7729.5579.4480.393.5*130.5*263.9
SD4.02.77.6242.5111.3277.133.412.210.41.61.23.9449.5149.9192.743.520.9103.4
  1. CSA: cross-sectional area, LG: lateral gastrocnemius, MG: medial gastrocnemius, S: soleus sub-tendon. *Significantly different from soleus sub-tendon after post hoc analysis (p<0.017).

Additional files

Supplementary file 1

Statistical analysis outcome of three sub-tendon mechanical properties.

(File separated uploaded).

https://cdn.elifesciences.org/articles/63204/elife-63204-supp1-v1.docx
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https://cdn.elifesciences.org/articles/63204/elife-63204-transrepform-v1.docx

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  1. Nai-Hao Yin
  2. Paul Fromme
  3. Ian McCarthy
  4. Helen L Birch
(2021)
Individual variation in Achilles tendon morphology and geometry changes susceptibility to injury
eLife 10:e63204.
https://doi.org/10.7554/eLife.63204