A chemical analysis of the clogging process of polymeric biliary endoprotheses

Ten UHMWPE hip inserts, five ethylene oxide and five gamma ray sterilised in air, were recovered during surgical revision after aseptic failure. Time in situ varied from 6 to 23 years. First implant was carried out for degenerative arthritis in all cases. The retrieved inserts were cut perpendicularly to the articulate surface; a series of 150 m slices were obtained from the cross section, studied with FTIR microscopy and extracted with cyclohexane for GC/MS and PY/GC/MS analysis. All retrieved PE components, whatever the sterilisation method, showed adsorbed materials on the surface, which were mainly synovial liquid protein components, and other products diffused in the bulk such as cholesterol, fatty ester of cholesterol and squalene, again from synovial liquid, the concentration of which varies according to the individual patient.