Pulsatile dynamic stiffness of cartilage-like materials and use of agarose gels to validate mechanical methods and models

Stiffness is a fundamental indicator of the functional state of articular cartilage. Reported test modes include compressive incremental strain to determine the equilibrium modulus, and sinusoidal strain to determine the dynamic modulus and stress/strain loss angle. Here, initial development is desc...

Full description

Saved in:
Bibliographic Details
Published in:Journal of biomedical materials research. Part B, Applied biomaterials Applied biomaterials, 2006-08, Vol.78B (2), p.347-357
Main Authors: Scandiucci de Freitas, P., Wirz, D., Stolz, M., Göpfert, B., Friederich, N.-F., Daniels, A. U.
Format: Article
Language:English
Subjects:
agarose
Animals
articular cartilage
Cartilage, Articular
Elasticity
Gels
Humans
hydrogel
Materials Testing
mechanical properties
Models, Biological
Sepharose
Stress, Mechanical
test method
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Stiffness is a fundamental indicator of the functional state of articular cartilage. Reported test modes include compressive incremental strain to determine the equilibrium modulus, and sinusoidal strain to determine the dynamic modulus and stress/strain loss angle. Here, initial development is described for a method recognizing that gait is pulsatile. Agarose gels have been used by others for validation or comparison of mechanical test methods and models for cartilage and proteoglycan aggregate. Accordingly, gels ranging from 0.5 to 20% agarose were prepared. Pulsatile stiffness in both indentation and unconfined compression were closely reproducible. Stiffness as a function of agarose concentration rose exponentially, as found using other methods. Indentation stiffness was higher than for unconfined compression and ranged from ∼2.0 kPa for 0.5% gel to ∼3800 kPa for 20% gel. Pulsatile dynamic stiffness appears to be a useful method, although further development is needed. Agarose gel stiffness values obtained by other methods were reviewed for comparison. Unfortunately, reported values for a given agarose concentration ranged widely (e.g. fourfold) even when test methods were similar. Causes appear to include differences in molecular weight and gel preparation time–temperature regimens. Also, agarose is hygroscopic, leading to unintended variations in gel composition. Agarose gels are problematic materials for validation or comparison of cartilage mechanical test methods and models. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2006
ISSN:1552-4973
1552-4981
DOI:10.1002/jbm.b.30494