The wear debris generated from UHMWPE (ultra high molecular weight polyethylene) has been recognised as one of the major causes of failure in THR (total hip replacement). GUR 1120 (compression moulded) and GUR 4150HP (ram extruded) which are currently the most frequently used materials in THR were studied in pin-on-plate wear test. The wear particles generated from this test were observed by scanning electron micrograph and analysed by image analysis. The results from this study showed that GUR 4150HP had superior wear resistance than GUR 1120 under relatively high wear factor conditions. These results also highlighted the importance of multidirectional motion and its effect on the wear rates of UHMWPE. The multidirectional motion tended to show a higher wear factor than previous studies using unidirectional motion conducted under otherwise similar conditions. The wear debris analysis conducted with the wear particles collected from unidirectional (relatively rough) pin-on-plate wear tests (GUR 1120 and GUR 4150HP) showed that the greatest number of particles had a size range of 0.1-0.5 micron followed by 0.5-1.0 micron, 1.0-5.0 microns and 5.0-10.0 microns, in both GUR 1120 and GUR 4150HP. However, comparing the masses of the wear particles, the bigger size range of greater than 10 microns, had the highest percent mass followed by 1.0-5.0 microns, 0.5-1.0 micron, 0.1-0.5 micron and 5.0-10.0 microns.
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