Cartilage substitutes are needed to replace cartilage
tissue, damaged in accidents or by pathologies (e.g., osteoarthritis).
Treatment by total hip replacement has disadvantages, particularly due to
immunological reactions to the implant’s wear debris. A promising alternative
is to replace damaged cartilage with substitutes based on hydrogel-type
material, designed to mimic the structure and properties of cartilage. In the
present study, Poly(ethylene glycol) (PEG)-based hydrogels cross-linked with
isophorone diisocyanate and amphiphilic interpenetrating polymer networks (IPNs)
of PEG with poly(methyl methacrylate) (PMMA) were prepared and characterized
for their mechanical and swelling properties. Twenty seven types of hydrogels
were synthesized, differing in their PEG molecular weight, cross-link density
and PMMA volume fraction. The properties measured were water content,
compression modulus, strength, fatigue durability and poroelastic properties
(hydraulic permeability and equilibrium modulus). The obtained results show
that low PEG Mw, high cross-link densities and high PMMA fraction, all lead to
high modulus and low water content, and that these properties can be controlled
independently by proper choice of the ingredients. Introduction of IPN greatly
improved the hydrogels’ strength. No reduction in the compression modulus,
resulting from fatigue damage, was evident. Poroelastic properties varied
non-monotonously with structural characteristics. Seven of the hydrogels prepared
were found to resemble cartilage in their water content, modulus and
poroelastic properties.
