Wear effects in retrieved acetabular UHMW-PE cups

There is an increasing awareness of the clinical problems associated with ultra-high-molecular-weight polyethylene (UHMW-PE) wear and failure in orthopaedics. This disadvantage is certainly promoted from the various oxidation process that can occur during prosthesis life. Scanning electron microscopy, IR-spectroscopy, and X-ray-photoelectron spectroscopy were employed to investigate the mechanism of polymer degradation. In particular, comparison among the spectra of starting and retrieved UHMW-PE components shows that the polymer oxidizes mainly in vivo. The data indicate that hydroxyl radicals are likely to be a major factor in degradation of the surface of this polymer, these groups are produced in vivo during the implantation time. Several other chemical groups, produced in the different steps of the prosthesis life, are contained in the material.