Implantation studies are a type of assay unique to medical device and biomaterials, having been specifically devised for those situations where an exogenous (and usually manmade) construct or material is enclosed in the body or partially entered into it by a breached surface. It is intended to assess the effects of devices (usually polymers or elastomers) which are in direct contact with living tissue (not including the skin). The effects of concern may be either short or long term, with a range of responses over the course of the host body and the device interacting with each other for various indicators of local tissue tolerance. Longer term studies are conducted for long term implants, and focus more on broader systemic effects and potential carcinogenicity. The whole field of implantation biology (which studies these interactions) is an extremely complete and active one (Greco, 1994; Black, 2000; Guelcher and Hollinger, 2006).