Surface interaction between hydrophilic gels and articular cartilage

Abstract

One of the important factors to be considered in the development of new implants for use in orthopedic surgery is the effect of the artificial material on opposing natural surfaces. In the case of materials which are intended for use as joint surface replacements, it is necessary to assess the effect of the material on the cartilage surfaces with which it will articulate in the joint. Rigid or abrasive materials tend to cause irreversible damage to opposing cartilage, whereas those which are too soft and pliable have a tendency to be eroded by the opposing natural surface. An ideal material for cartilage replacement would be resilient enough to avoid damaging the opposing cartilage and yet sufficiently strong to resist wear. It is also necessary that such a material be of a form that could be easily implanted in bone and, once implanted, would remain fixed in place for long periods of time. Compounds for potential implantation which seem to fulfill some of these requirements are the hydrophilic methacrylates. This group is one of a number of methacrylate polymers which has been shown to have a relatively high degree of biocompatibility with mammalian tissue [l]. Among the hydrophilic gels with desirable characteristics are two specific polymers named poly-(2hydroxyethyl methacrylate) or polyHEMA and Hydron N. These polymers have the capacity to expand in a fluid medium as a result of the absorption of water and dissolved solutes. As a result of this expansion they change from hard, brittle substances