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Effects of glycation on dynamic mechanical properties and penetration of articular cartilage

Articular cartilage is a heterogeneous structure that has multiphase mechanical properties. The mechanical properties are derived from the interactions of three components of articular cartilage; collagen fibers, GAGs, and water. This thesis was designed to explore the contributions of some of these components by selectively altering their structure or the load they carry, while concurrently examining the effects of nonenzymatic glycation on cartilage. The first set of experiments varied the area of load on cartilage and thereby the volume of water displaced to examine the contributions of fluid flow to the relaxation of articular cartilage. The results demonstrated an indentation load area effect for articular cartilage. Relaxation was faster with smaller indenter size, consistent with smaller effects of fluid flow and relatively fast relaxation of the solid matrix. The data illustrate the varying modes of relaxation associated with indentation and full surface compression. Secondly, the protein matrix was modified via glycation to crosslink the solid matrix and simulate cartilage changes that occur with aging. Control specimens swelled dramatically during storage, and decreased in the stiffness. Glycated specimens did not swell and maintained stiffness during storage. Thirdly, penetration testing was used to estimate the failure properties of cartilage with and without the superficial zones and glycation. There was no significant change in the failure properties associated with removal of the superficial zone. However, glycation caused the cartilage to become more brittle and weak, failing under less stress and deformation than non-glycated specimens. The combination of the experiments illustrated the ability of glycation to maintain the elastic, but not failure, mechanical properties of articular cartilage
Thesis, Dissertation, English, 2010
University of California, Davis