Simulator testing of total knee replacements

In order to determine the effect of improvements in design and materials on wear of total knee replacement, a valid test method is required. This test method should reproduce the wear patterns seen on retrieved knee replacements. We have tested various designs of implants using a force-control knee simulator and analysed the wear on these implants. The tests were conducted in 50 per cent bovine serum for up to ten million cycles. On condylar replacements, wear was associated with scratching and burnishing. Wear rates between different designs could be discriminated. Delamination wear occurred only in those samples which had been artificially aged. Tests showed that wear on a meniscal knee design equalled that, or was greater than that, observed on a condylar design. On meniscal designs wear was associated mainly with the meniscal bearing surface.