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Non-uniform displacements within the Achilles tendon observed during passive and eccentric loading
Laura Chernak Slane1, Darryl G Thelen2
1Department of Biomedical Engineering, University of Wisconsin-Madison, WI, USA.
Journal of Biomechanics
|August 25, 2014
Summary
Achilles tendon tissue displacement is non-uniform, with deeper regions moving more than superficial ones. Eccentric loading and knee posture significantly influence these displacement patterns during ankle motion.
Area of Science:
- Biomechanics
- Musculoskeletal research
- Tendon mechanics
Background:
- The Achilles tendon's complex structure may lead to varied tissue displacement under load.
- Understanding in vivo tendon deformation is crucial for injury prevention and rehabilitation.
Purpose of the Study:
- To investigate Achilles tendon tissue displacement patterns.
- To compare displacement under passive versus eccentric loading.
- To assess the influence of knee posture on tendon displacement.
Main Methods:
- Nine healthy adults underwent cyclic ankle motion (25° range, 0.5 Hz).
- Eccentric loading and passive motion were applied with varying knee postures (30° vs. 90°).
- Ultrasound elastography analyzed radiofrequency data to track tissue displacement in the distal Achilles tendon.
Main Results:
- Non-uniform displacement observed, with deeper tendon regions showing greater displacement (0.9–2.6 mm).
- Eccentric loading generally reduced tissue displacement compared to passive motion.
- Extended knee posture (30°) resulted in greater overall tissue displacement than flexed posture (90°).
Conclusions:
- Achilles tendon exhibits non-uniform, posture-dependent deformation under in vivo loading.
- Observed patterns may indicate fascicular sliding between gastrocnemius and soleus muscle contributions.
- Findings provide insights into tendon mechanics during functional activities.
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