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No functional benefit of larger femoral heads and alternative bearings at 6 months following primary hip replacement

Lookup NU author(s): Dr Simon Jameson, Professor James Mason, Paul Baker, Professor Paul Gregg, Professor David Deehan, Michael Reed


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Background and purpose - There has been a recent trend towards the use of greater femoral head sizes in an attempt to improve function and enhance stability after primary hip replacement. This has been associated with the use of alternative bearings, theoretically to reduce wear and improve implant longevity.Methods - We examined the influence of these variables on patient-reported outcome measures (PROMs) for a consecutive series of primary hip replacements using National Joint Registry (NJR) and PROMs-linked data. To minimize the confounding influence of implant design factors, the single most commonly used brand in England and Wales (DePuy Corail Pinnacle) was examined. Improvement in patient hip-specific outcomes (Oxford hip score, OHS), general health outcomes (Euroqol, EQ-5D), and rates of self-reported complications (bleeding, wound problems, readmission, and reoperation) were compared for different head sizes (28-mm, 32-mm, and 36-mm) and bearings (metal-on-polyethylene (MoP), ceramic-on-polyethylene (CoP), and ceramic-on-ceramic (CoC)), adjusting for differences in case mix.Results - At a mean follow-up of 7 months, improvements in OHS and EQ5D index were similar for 28-mm and 36-mm heads. A 32-mm head was associated with poorer function (OHS: 20, 99% CI: 19-21, p = 0.002; EQ5D index: 0.39, 99% CI: 0.36-0.42, p = 0.004), although these small differences may not be of clinical importance. There were no statistically significant benefits of either CoP or CoC bearings compared to a MoP bearing. Complication rates were similar within comparisons of head sizes or bearings.Interpretation - In this short-term study, we did not find any functional benefits of larger head sizes or alternative bearings, after adjusting for other influences. We question their use in routine primary hip replacement given the lack of evidence of improved long-term survival in the literature.

Publication metadata

Author(s): Jameson SS, Mason JM, Baker PN, Gregg PJ, Deehan DJ, Reed MR

Publication type: Article

Publication status: Published

Journal: Acta Orthopaedica

Year: 2015

Volume: 86

Issue: 1

Pages: 32-40

Print publication date: 01/02/2015

Acceptance date: 19/05/2014

ISSN (print): 1745-3674

ISSN (electronic): 1745-3682

Publisher: Informa Healthcare


DOI: 10.3109/17453674.2014.972259


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