On how degenerative changes influence the microstructural response of articular cartilage to mechanical loading

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dc.contributor.advisor Thambyah, A en
dc.contributor.advisor Broom, ND en
dc.contributor.author Nickien, Mieke en
dc.date.accessioned 2017-01-08T20:45:06Z en
dc.date.issued 2016 en
dc.identifier.uri http://hdl.handle.net/2292/31495 en
dc.description.abstract The general objective of this PhD project was to understand how degenerative changes associated with collagen network de-structuring in articular cartilage (AC) influence its microstructural response to loading. Two main testing methods were employed: Firstly, cartilage-on-bone blocks were compressed using an indenter incorporating a central relief channel to allow the AC to bulge into this channel during creep compression to an extent governed by its inherent matrix constraints. Secondly, transverse stretching and swelling experiments were conducted using isolated cartilage samples consisting exclusively of radial zone matrix. Three channel indentation studies are described. In the first study, a single radial incision was made in the AC to varying depths with respect to its zonal structure. This resulted in an altered pattern of matrix shear following compression whose intensity varied with incision depth. The second study showed that a reduced water-binding potential in otherwise intact cartilage matrix did not lead to altered patterns of shear, but led to surface rupture and abnormal matrix collapse. The important role of the osteochondral junction in the development of internal matrix shear was demonstrated in the third study. De-structured isolated cartilage samples had a decreased transverse stiffness compared to structurally intact samples, despite their similar glycosaminoglycan content. It was shown that this resulted from the reduced level of fibrillar interconnectivity in the former, which also led to a loss of functional coupling between the collagen network and the proteoglycans. The proteoglycans in the degenerate matrix did, however, still contribute significantly to tissue stiffness. Further, it was shown that tissue swelling and the maximum tensile stiffness in isolated cartilage samples are more reliable indicators of its degenerative state than could be obtained from a measurement of its lower isostrain modulus. The results of the studies described in this thesis have increased our understanding of the mechano-structural mechanism underlying the degenerative cascade and provide important implications for the development of cartilage replacements and computational models. An intact collagen network incorporating a functional zonal distribution, sufficient fibrillar interconnectivity, and proper attachment to the subchondral bone are all critical for the containment of matrix water and development of internal shear. en
dc.publisher ResearchSpace@Auckland en
dc.relation.ispartof PhD Thesis - University of Auckland en
dc.relation.isreferencedby UoA99264936912002091 en
dc.rights Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated. Previously published items are made available in accordance with the copyright policy of the publisher. en
dc.rights.uri https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm en
dc.rights.uri http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ en
dc.title On how degenerative changes influence the microstructural response of articular cartilage to mechanical loading en
dc.type Thesis en
thesis.degree.discipline Engineering en
thesis.degree.grantor The University of Auckland en
thesis.degree.level Doctoral en
thesis.degree.name PhD en
dc.rights.holder Copyright: The author en
dc.rights.accessrights http://purl.org/eprint/accessRights/OpenAccess en
pubs.elements-id 605598 en
pubs.record-created-at-source-date 2017-01-09 en

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http://creativecommons.org/licenses/by-nc-sa/3.0/nz/ Except where otherwise noted, this item's license is described as http://creativecommons.org/licenses/by-nc-sa/3.0/nz/


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