COMPARISON BETWEEN IN-VITRO AND IN-VIVO UHMW-PE DEGRADATION

There is an increasing interest in orthopedics for clinical problems a ssociated with wear and failure of ultra-high-molecular-weight (UHMW) polyethylene devices. Wear not only affects the implant performance bu t, more importantly, produces the release of particulate debris in the surrounding tissues and fluids. The debris in turn cause a deleteriou s biological response that can include an inflammatory reaction with s ubsequent loosening of the implant components. Surface wear is certain ly promoted from the oxidation process that can occur during the prost hesis' life. However, the oxidation mechanism involved during the impl antation period has not been described yet for the UHMW-polyethylene d evices. Here, the comparison of FT-IR spectra of a retrieved acetabula r cup (9 years in a human body) and thin UHMW-PE films treated respect ively with: H2O2, KO2/THF, and Fe[II]/H2O2 solutions indicates the eff ect of the high reactive hydroxyl radicals as the most important cause of in vivo polymer degradation.