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Lookup NU author(s): Timothy Brock,
Professor Stephen Rushton,
Professor Tom Joyce,
Professor David Deehan,
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Taper wear at the head-neck junction is a possible cause of early failure in large head metal-on-metal (LH-MoM) hip replacements. We hypothesized that: (i) taper wear may be more pronounced in certain product designs; and (ii) an increased abductor moment arm may be protective. The tapers of 104 explanted LH-MoM hip replacements revised for adverse reaction to metal debris (ARMD) from a single manufacturer were analyzed for linear and volumetric wear using a co-ordinate measuring machine. The mated stem was a shorter 12/14, threaded trunnion (n=72) or a longer, smooth 11/13 trunnion (n=32). The abductor moment arm was calculated from pre-revision radiographs. Independent predictors of linear and volumetric wear included taper angle, stem type, and the horizontal moment arm. Tapers mated with the threaded 12/14 trunnion had significantly higher rates of volumetric wear (0.402mm(3)/yr vs. 0.123mm(3)/yr [t=-2.145, p=0.035]). There was a trend to larger abductor moment arms being protective (p=0.055). Design variation appears to play an important role in taper-trunnion junction failure. We recommend that surgeons bear these findings in mind when considering the use of a short, threaded trunnion with a cobalt-chromium head. (c) 2015 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 33:1868-1874, 2015.
Author(s): Brock TM, Sidaginamale R, Rushton S, Nargol AVF, Bowsher JG, Savisaar C, Joyce TJ, Deehan DJ, Lord JK, Langton DJ
Publication type: Article
Publication status: Published
Journal: Journal of Orthopaedic Research
Print publication date: 01/12/2015
Online publication date: 25/07/2015
Acceptance date: 16/06/2015
ISSN (print): 0736-0266
ISSN (electronic): 1554-527X
Publisher: John Wiley & Sons, Inc.
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