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Lubricants 2015, 3(2), 244-255;

In Vitro Wear Testing of a CoCr-UHMWPE Finger Prosthesis with Hydroxyapatite Coated CoCr Stems

School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne, England NE1 7RU, UK
Upper Limb Research Unit, Wrightington Hospital, Wigan, England WN6 9EP, UK
Author to whom correspondence should be addressed.
Academic Editors: Amir Kamali and J. Philippe Kretzer
Received: 3 March 2015 / Revised: 27 March 2015 / Accepted: 2 April 2015 / Published: 13 April 2015
(This article belongs to the Special Issue Tribological Performance of Artificial Joints)
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A finger prosthesis consisting of a Cobalt-chromium (CoCr) proximal component and an Ultra-high-molecular-weight-polyethylene (UHMWPE) medial component (both mounted on hydroxyapatite coated stems) was evaluated to 5,000,000 cycles in an in vitro finger simulator. One “test” prosthesis was cycled through flexion-extension (90°–30°) with a dynamic load of 10 N, whilst immersed in a lubricant of dilute bovine serum. Additionally, a static load of 100 N was applied for 45 s every 3000 cycles to simulate a static gripping force. A second “control” prosthesis was immersed in the same lubricant to account for absorption. Gravimetric and Sa (3D roughness) measurements were taken at 1,000,000 cycle intervals. Micrographs and Sa values revealed negligible change to the CoCr surfaces after 5,000,000 cycles. The UHMWPE also exhibited no distinctive Sa trend, however the micrographs indicate that polishing occurred. Both the CoCr and UHMWPE test components progressively decreased in weight. The CoCr control component did not change in weight, whilst the UHMWPE component gained weight through absorption. To account for the disparity between surface and gravimetric results, the hydroxyapatite coatings were examined. Micrographs of the test stems revealed that the hydroxyapatite coating was partially removed, whilst the micrographs of the control stems exhibited a uniform coating. View Full-Text
Keywords: wear analysis/testing; joint simulators; biotribology; biomechanical testing/analysis; surfaces wear analysis/testing; joint simulators; biotribology; biomechanical testing/analysis; surfaces

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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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Naylor, A.; Talwalkar, S.C.; Trail, I.A.; Joyce, T.J. In Vitro Wear Testing of a CoCr-UHMWPE Finger Prosthesis with Hydroxyapatite Coated CoCr Stems. Lubricants 2015, 3, 244-255.

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