Individual variation in Achilles tendon morphology and geometry changes susceptibility to injury
- Research Department of Orthopaedics and Musculoskeletal Science, University College London, Royal National Orthopaedic Hospital, United Kingdom
- Department of Mechanical Engineering, University College London, United Kingdom
- Pedestrian Accessibility and Movement Environment Laboratory, Department of Civil, Environmental and Geomatic Engineering, University College London, United Kingdom
Figures
Figure 1
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.
Figure 3
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.
Figure 4
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.
Figure 5
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.
Figure 6
Group differences in normalised soleus junction displacement during different stimulation trials.
Figure 7
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.
| Specimen | CSA (mm2) | Failure force (N) | Ultimate stress (MPa) | Ultimate strain (%) | Young’s modulus (MPa) | Stiffness (N/mm) | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| (age–sex) | LG | MG | S | LG | MG | S | LG | MG | S | LG | MG | S | LG | MG | S | LG | MG | S |
| 69 M | 13.6 | 14.5 | 39.2 | 325.0 | 402.2 | 1701.2 | 24.0 | 27.7 | 45.3 | 9.7 | 10.0 | 19.1 | 353.9 | 375.8 | 399.4 | 79.9 | 97.6 | 260.6 |
| 78 F | 12.4 | 10.8 | 20.6 | 154.7 | 571.1 | 1155.6 | 12.5 | 52.6 | 56.2 | 11.6 | 8.9 | 17.5 | 175.0 | 771.1 | 421.1 | 36.7 | 145.6 | 167.8 |
| 84 F | 5.7 | 10.7 | 30.9 | 503.6 | 621.8 | 1577.0 | 89.0 | 58.3 | 51.0 | 8.9 | 12.2 | 10.4 | 1231.5 | 636.9 | 734.9 | 118.2 | 121.4 | 385.1 |
| 85 F | 10.4 | 14.0 | 38.2 | 787.5 | 688.3 | 1090.9 | 75.8 | 49.0 | 28.6 | 11.9 | 10.6 | 15.8 | 853.6 | 617.2 | 239.9 | 151.7 | 144.7 | 156.6 |
| 87 M | 4.6 | 17.0 | 35.2 | 301.6 | 647.7 | 1578.5 | 65.9 | 38.1 | 44.9 | 8.2 | 10.2 | 10.8 | 1033.4 | 496.2 | 606.2 | 80.9 | 143.0 | 349.6 |
| Mean | 9.3* | 13.4* | 32.8 | 414.5* | 586.2* | 1420.6 | 53.4 | 45.1 | 45.2 | 10.1 | 10.4 | 14.7 | 729.5 | 579.4 | 480.3 | 93.5* | 130.5* | 263.9 |
| SD | 4.0 | 2.7 | 7.6 | 242.5 | 111.3 | 277.1 | 33.4 | 12.2 | 10.4 | 1.6 | 1.2 | 3.9 | 449.5 | 149.9 | 192.7 | 43.5 | 20.9 | 103.4 |
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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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Transparent reporting form
- https://cdn.elifesciences.org/articles/63204/elife-63204-transrepform-v1.docx
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Individual variation in Achilles tendon morphology and geometry changes susceptibility to injury
eLife 10:e63204.
https://doi.org/10.7554/eLife.63204
