A combined XPS-SEM/EDX investigation on explanted UHMW polyethylene acetabular cups: possible role of silicon traces in the wear debris

An investigation was started aimed at a better understanding of the complex phenomena leading to chemical degradation and morphological deterioration of UHMW polyethylene cups in total hip prostheses. Analysis was performed o n retrieved implants which needed revision due to inflammation and pain pro blems. Preliminary results obtained by parallel XPS and SEM/EDX experiments gave evidence, for the first time, that silicon traces are involved in the process of particle formation and segregation onto the surface of the cups . The extent of modification of the surface chemical composition of cups an d the process of particle segregation seem to be correlated to both the imp lant time and to some particular features of patient (age, activity, style of life, etc.). Investigation on a large number of samples is in progress i n order to test this hypothesis. The results obtained so far confirmed the potential of surface spectroscopies (XPS) in biomaterial investigations. (C ) 2001 Kluwer Academic Publishers.