A comparison of the wear of cross-linked polyethylene against itself under reciprocating and multi-directional motion with different lubricants

A two-piece, silane cross-linked polyethylene (XLPE) finger prosthesis has been developed. To further the knowledge of the wear of XLPE against itself, a number of ‘pin-on-plate’ wear tests were undertaken, under different conditions of lubrication. These were distilled water, bovine serum and dry conditions. A second group of tests were then carried out, in which multi-directional motion was applied to the test pins. All tests had XLPE pins loaded at 40 N rubbing against XLPE plates. All the XLPE came from the same batch. In all tests, pin wear was much less than plate wear. Under reciprocation only, the least wear was found when bovine serum was the lubricant (k=0.6×10−6 mm3/N m) and the maximum wear was when distilled water was the lubricant (k=5.8×10−6 mm3/N m). When multi-directional motion was applied to the test pins, increased wear occurred under lubrication with bovine serum (k=3.4×10−6 mm3/N m). Surprisingly, wear decreased when distilled water was used (k=0.7×10−6 mm3/N m), yet wear factors remained similar in the ‘dry’ test (k=0.7×10−6 mm3/N m). The dry tests had remarkably low wear.