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Lubricants 2018, 6(1), 1; https://doi.org/10.3390/lubricants6010001

Acetabular Cups in 60 mm Metal-on-Metal Bearings Subjected to Dynamic Edge-Loading with 70° Peak-Inclination in 10-Million Cycle Simulator Study

1
Department of Orthopedics, Loma Linda University Medical Center, Loma Linda, CA 92350, USA
2
DARF Retrieval Center, Colton, CA 92324, USA
3
Consultant Orthopedic Surgeon, Spire Hospital, Bristol BS6 6UT, UK
4
Empire Orthopedics, 900 E Washington Blvd, Colton, CA 92324, USA
*
Author to whom correspondence should be addressed.
Received: 25 October 2017 / Revised: 5 December 2017 / Accepted: 8 December 2017 / Published: 21 December 2017
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Abstract

Wear simulation of total-hip arthroplasty (THA) involves hip biomechanics, tribology, bearing designs and cup wear-patterns. This is the first demonstration of cup edge-loading using the “Inverted-cup” test mode. Benefits included, (i) clinically relevant wear-patterns, and (ii) cup inclinations varying from ideal to edge-loaded during each 1-s simulator cycle. The 60 mm head and cup bearings in metal-on-metal (MOM) hip joints showed run-in and steady-state wear phases to 10-million cycles (Mc). MOM edge-wear was not unduly high at 1.7 mm3/Mc overall, this 3-fold higher than 60 mm MOM study without edge-loading. One MOM outlier averaged 2.7 mm3/Mc, this representing the break-away wear (BAW) phenomena. A surprising result was that cups contributed 75–93% of total wear. The most disturbing conclusion from review of laboratory studies was that MOM wear-rates varied 1 to >30 mm3/Mc for reasons not understood. These data suggested a new hypothesis, that MOM bearings were very sensitive to external stimuli, be they simulator artifact or patient related. View Full-Text
Keywords: CoCr; hip-joint bearings; simulator; serum lubricant; 3rd-body wear CoCr; hip-joint bearings; simulator; serum lubricant; 3rd-body wear
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Clarke, I.C.; Halim, T.; Smith, E.J.; Donaldson, T.K. Acetabular Cups in 60 mm Metal-on-Metal Bearings Subjected to Dynamic Edge-Loading with 70° Peak-Inclination in 10-Million Cycle Simulator Study. Lubricants 2018, 6, 1.

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