Isolation and morphological characterisation of UHMWPE wear debris generated in vitro

Wear tests are generally carried out on materials used in prosthetic hip im plants, in order to obtain a better understanding of the tribological proce sses involved and improve the quality control of joint prostheses, directed towards reducing the risk of implant failure of innovative prostheses. Cer amic femoral heads of mixed alumina-zirconia oxides as well as zirconia and alumina single oxide heads were tested against UHMWPE acetabular cups in a hip joint simulator. Polyethylene cups and ceramic femoral heads were moun ted in a simulator apparatus moving according to a sinusoidal function, und er load and in the presence of bovine calf serum as lubricant. Wear particl es were isolated from the bovine calf serum collected during the wear tests . An easy to follow method was used to separate the wear particles from the lubricant. Chemical digestive methods were used to separate the wear parti cles from the lubricant and the isolated particles were studied using scann ing electron microscopy. The morphologies of the polyethylene debris showed considerable differences, both in size and shape of the particles, as a fu nction of the coupled head material. (C) 2001 Elsevier Science Ltd. All rig hts reserved.