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Shorter, rough trunnion surfaces are associated with higher taper wear rates than longer, smooth trunnion surfaces in a contemporary large head metal-on-metal total hip arthroplasty system

Lookup NU author(s): Timothy Brock, Professor Stephen Rushton, Professor Tom Joyce, Professor David Deehan, David Langton

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Abstract

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.

Publication metadata

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

Year: 2015

Volume: 33

Issue: 12

Pages: 1868-1874

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.

URL: http://dx.doi.org/10.1002/jor.22970

DOI: 10.1002/jor.22970

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