M.S. Thesis Presentation by Jason A. Stammen
Tuesday, April 11, 2000

(Dr. Robert Guldberg, advisor)

"Mechanical Performance of a Novel Biomaterial for Articular Cartilage Replacement"

Abstract

Recent strong interest in the development of novel synthetic hydrogels and hydrogel composites can be attributed to their unique combination of properties, including biocompatibility, permeability, hydrophilicity, and low coefficient of friction.  However, insufficient mechanical properties have severely limited the use of hydrogels for load-bearing applications such as the replacement of damaged or diseased tissues.

Poly(vinyl alcohol) (PVA) hydrogels have been specifically proposed as promising prosthetic biomaterials to replace articular cartilage.  One such PVA hydrogel displays similarities to natural cartilage tissue in terms of water content and, furthermore, shows promise in terms of its mechanical integrity and biocompatibility.  The primary purpose of this thesis was to develop test protocols and evaluate the functional, intrinsic, and dynamic properties of this material.  The current properties of the material were compared to those of natural articular cartilage (bovine and human) and the effect of parameters such as confinement, water content, and loading frequency on the material characteristics were investigated.  The functional properties included the material response to compressive and shear stresses, as well as the point of plastic failure.  The intrinsic properties described how the solid matrix and interstitial fluid interact to create the nonlinear, viscoelastic behavior in compression.  Finally, the fatigue properties quantified the mechanical behavior during long-term cyclic compressive loading.

A second objective of this study was to generate an efficient procedure that transforms digital CT data from a patient into an accurate implant shape through solid modeling and rapid prototyping.  A prototype implant was designed, fabricated, and evaluated.