The influence of sterilization method on wear performance of the low contact stress total knee system

Biocompatibility of Supercritical CO2-Treated Titanium Implants in a Rat Model

Supercritical phase CO2 is a promising method for sterilizing implantable devices and tissue grafts. The goal of this study is to evaluate the biocompatibility of titanium implants sterilized by supercritical phase CO2 in a rat subcutaneous implantation model. At 5 weeks post implantation titanium implants sterilized by supercritical phase CO2 produce a soft tissue reaction that is comparable to other methods of sterilization (steam autoclave, ultraviolet light radiation, ethylene oxide gas, and radio-frequency glow-discharge), as indicated by the thickness and density of the foreign body capsule, although there were some differences on the capillary density. Overall the soft tissue response to the implants was similar among all methods of sterilization, indicating supercritical phase CO2 treatment did not compromise the biocompatibility of the titanium implant.

Effects of sterilization on implant mechanical property and biocompatibility

This article concisely reviews the effects of sterilization on the mechanical properties and surface chemistries of implantable biomaterials. This article also summarizes the biological effects of the sterilization-related changes in the implant. Because there are so many different types of implant materials currently in use (including metals, polymers, and diverse biological materials), the response of tissue to these different materials varies dramatically. This review further discusses the effects of sterilization on in vivo and in vitro tissue response specifically to implantable metals and polyethylene, with the possibility of future biocompatibility testing of the implants sterilized with supercritical phase carbon dioxide sterilization.

Quantifying the effect of resin type and sterilization method on the degradation of ultrahigh molecular weight polyethylene after 4 years of real-time shelf aging

Alternative sterilization methods including ethylene oxide, gas plasma, and gamma-radiation in an inert environment were implemented in the late 1990s, to limit oxidative degradation of ultrahigh molecular weight polyethylene (PE). There was also a simultaneous transition to PE resins that did not contain calcium stearate. Shelf storage duration of PE inserts following gamma-irradiation in air has been correlated to poor clinical performance and increased wear. This study aimed to determine how sterilization method and resin type influenced degradation of PE after 4 years of real-time shelf aging. It was hypothesized that gamma-irradiation and stearate containing resins would incur significantly more degradation than nonradiated, stearate-free resins. Gamma-irradiated PE samples in air and nitrogen had a significantly increased density and oxidation index, compared to nonirradiated PE after 4 years of shelf aging. Alternative sterilization methods such as ethylene oxide and gas plasma appeared to have significantly less oxidation regardless of PE resin type. A partial correlation demonstrated that density and oxidation index were not correlated (r(2) = 0.079) when examining the influence of sterilization method. The data supported that after 4 years of real-time shelf aging, the type of sterilization method had a larger influence on PE degradation than resin type.