Comparative biotolerance of polyacrylamide-agarose gel, silicone rubber and microporous PTFE as soft tissue implants

A comparative study has been carried out on the biotolerance to subcutaneous, intramuscular and intraperitoneal implants of silicone rubber, microporous PTFE and polyacrylamide-agarose gel for 6 wk in the rat. Assessment was quantitative histology for capsule thickness, fibroblast density, mononuclear cell density, multinucleated giant cell density and also collagen packing density. The trial polymers were compared to historical data on healing in dummy procedures and on two hydrophilic graft copolymers of high biotolerance namely polyethylene-acrylic acid and microporous polypropylene-acrylic acid. The rank ordering of the trial polymers for all criteria except collagen packing, was for the least response to be to polyacrylamide-agarose and the most to silicone rubber, with the differences being significant (p less than 0.05) for capsule thickness and mononuclear cell density. Polyacrylamide-agarose was similar in response to the two hydrophilic copolymers; microporous PTFE was slightly more reactive and silicone rubber was significantly more reactive (p less than 0.05).