Tissue-implant response following soft tissue implantation of poly-L-lysine coated UHMW-polyethylene into adult male rats.

It is well demonstrated in the literature that polyethylene materials used in orthopedic applications are highly compatible and non-immunogenic with host tissues. However, recent studies in our laboratory have demonstrated the need for further study of these devices in vivo to further elucidate the mechanisms involved in biocompatibility. The purpose of this investigation was to study the tissue-implant response resulting from the implantation of ultra high molecular weight polyethylene (PE) coated with poly-L-lysine at 90 days post-implantation. In this investigation, implants of PE coated with poly-L-lysine and saline were implanted into 8 adult male rats subcutaneously (S/C) and intraperitoneally (I/P). At 90 days post-implantation, the animals were euthanized; and the PE devices, the fibrous tissue, and vital organs were harvested. Evaluation of routinely stained sections (5 microns, Hematoxylin & Eosin) of the fibrous tissue capsule surrounding the PE implants revealed the following: 1) all the devices had fibrous connective tissue capsules of slightly varying degrees of thickness surrounding them present at the time of sacrifice, 2) the thickness of the fibrous tissue capsule was dependent on the site of implantation and type of coating, 3) the thickness of the fibrous tissue capsules around the subcutaneous devices differed markedly than those retrieved from the peritoneal cavity, and 4) there were statistically significant differences (T-test, p < 0.05) in the numbers and types of cellular components with respect to implantation site and type of coating.