A Study of the Wear Characteristics of Sliding Pairs of High Density Polycrystalline Aluminium Oxide with Particular Reference to Their Use in Total Replacement Human Joints

Abstract

The introduction of ceramic components into total replacement joints for the human body in the last decade has attracted considerable attention. In most cases in which a ceramic component is used a ceramic femoral head is located on a metallic femoral stem, whilst the acetabular cup is made from ultra high molecular weight polyethylene. In some designs a ceramic acetabular cup is used in association with the ceramic femoral head. A study of the basic wear characteristics of sliding pairs of high density polycrystalline ceramics is reported in this paper. Tests have been carried out under both ‘dry’ and ‘wet’ (distilled water) conditions in a tri-pin-on-disc wear testing machine. It is shown that sliding pairs of alumina ceramics exhibit remarkably low wear under dry conditions when subjected to small loads, but that high loads lead to rapid deterioration of the interacting surfaces and the onset of very high wear rates. The presence of distilled water generally permits smooth sliding at higher loads than are possible under dry conditions, but the wear rate increases by a factor of about ten over those encountered at low loads in air. The slight advantage of sliding pairs of alumina over high density polyethylene sliding on stainless steel as far as wear is concerned is not evident if the comparison is made with high density polyethylene sliding on high density ceramic in the presence of distilled water.