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Mechanical properties of collagen fascicles from the rabbit patellar tendon
E Yamamoto1, K Hayashi, N Yamamoto
1Department of Mechanical Engineering, Faculty of Engineering Science, Osaka University, Japan.
Journal of Biomechanical Engineering
|March 18, 1999
Summary
Collagen fascicles from rabbit patellar tendons exhibit distinct tensile and viscoelastic properties compared to bulk tendons. These differences in mechanical behavior are crucial for understanding tendon function and injury.
Area of Science:
- Biomedical Engineering
- Materials Science
- Biomechanics
Background:
- Tendon mechanical properties are critical for joint function.
- Understanding the behavior of individual collagen fascicles is essential for a comprehensive view of tendon mechanics.
- Previous studies have primarily focused on bulk tendon properties.
Purpose of the Study:
- To investigate the tensile and viscoelastic properties of individual collagen fascicles from rabbit patellar tendons.
- To compare the mechanical properties of fascicles with those of the bulk patellar tendon.
- To explore the influence of strain rate and stress relaxation on fascicle behavior.
Main Methods:
- Utilized a novel micro-tensile tester to analyze collagen fascicles (approx. 300 microns diameter).
- Employed a video dimension analyzer with a CCD camera and microscope to determine cross-sectional areas.
- Conducted tensile tests at varying strain rates (1.5%/s, 1%/s, 0.01%/s) and stress relaxation tests (300 seconds).
Main Results:
- Fascicle tensile properties showed no significant variation across medial-to-lateral locations.
- At 1.5%/s strain rate, fascicles exhibited a tangent modulus of 216 ± 68 MPa, tensile strength of 17.2 ± 4.1 MPa, and strain at failure of 10.9 ± 1.6%.
- Fascicle tensile strength and strain at failure were substantially different from bulk tendons (42% and 179% respectively).
- Higher strain rates (1%/s vs 0.01%/s) increased tangent modulus and tensile strength by 35%, while strain at failure remained constant.
- Stress relaxation tests showed a ~25% stress reduction over 300 seconds.
- Fascicle viscoelasticity and strain rate sensitivity differed significantly from bulk tendons.
Conclusions:
- Individual collagen fascicles possess unique mechanical and viscoelastic properties distinct from the bulk patellar tendon.
- Differences may stem from ground substances, inter-fascicular interactions, and collagen fibril crimp structure.
- These findings provide critical insights into the micromechanical behavior of tendons and their functional implications.