tests is due to the fact that the tribological endurance limit is being
approached. When this limit is exceeded, the wear rate will be
high and its variation low. In the present study, the limit was
exceeded by increasing the load by 50%. At 70° inclination, 2 kN
peak load resulted in high variation, whereas 3 kN produced uniform,
high wear. When the conditions are well below the limit,
wear and its variation are low. With 50 mm diameter Metasul
MoMs (n¼3), 2 kN peak load and 48° inclination, the steady-state
wear rate was 0.8970.13 mg/10
6
cycles only [1].
The mean wear rate value observed in test 2, 167 mg/10
cycles
was still only half of the highest value measured by Essner et al.
[7], 332 mg/10
6
cycles for one exceptional MoM prosthesis. They
ran eight similar 40 mm diameter MoMs (as-cast, high-carbon
CoCr alloy, ASTM F-75) with 0.1–0.18 mm diametral clearance in
the MTS simulator at c. 20° inclination angle (estimated from Fig. 1
of the paper; edge loading therefore was not possible), with
2.45 kN peak load, and in diluted serum lubricant similar to that
used in the present study. While five of the prostheses showed