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Copyright ©The Author(s) 2016. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. May 18, 2016; 7(5): 272-279
Published online May 18, 2016. doi: 10.5312/wjo.v7.i5.272
Management of metal-on-metal hip implant patients: Who, when and how to revise?
Reshid Berber, John A Skinner, Alister J Hart
Reshid Berber, John A Skinner, Alister J Hart, Joint Reconstruction Unit, Institute of Orthopaedics and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, London HA7 4LP, United Kingdom
Author contributions: All listed authors were involved in the literature review and writing of this manuscript; all three authors contributed equally to this work.
Conflict-of-interest statement: The authors declare that they no conflict of interest; Skinner JA and Hart AJ have a consultancy agreement with Depuy and Stryker for metal on metal hip retrieval work.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Reshid Berber, MBBS, BSc (Hons), MRCS (Eng), Orthopaedic Registrar and Research Fellow, Joint Reconstruction Unit, Institute of Orthopaedics and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, London HA7 4LP, United Kingdom. reshidb@gmail.com
Telephone: +44-20-89095621 Fax: +44-20-89095100
Received: July 29, 2015
Peer-review started: July 29, 2015
First decision: September 30, 2015
Revised: January 12, 2016
Accepted: March 7, 2016
Article in press: March 9, 2016
Published online: May 18, 2016
Processing time: 286 Days and 4.2 Hours
Abstract

The debate on how best to manage patients with metal-on-metal (MOM) hip implants continues. With over 1 million patients affected worldwide, the impact is far reaching. The majority of the aggressive failures of MOM hip implants have been dealt with by revision hip surgery, leaving patients with a much more indolent pattern of failure of devices that have been in situ for more than 10 years. The longer-term outcome for such patients remains unknown, and much debate exists on how best to manage these patients. Regulatory guidance is available but remains open to interpretation due to the lack of current evidence and long-term studies. Metal ion thresholds for concern have been suggested at 7 ppb for hip resurfacing arthroplasty and below this level for large diameter total hip arthroplasties. Soft tissue changes including pseudotumours and muscle atrophy have been shown to progress, but this is not consistent. New advanced imaging techniques are helping to diagnose complications with metal hips and the reasons for failure, however these are not widely available. This has led to some centres to tackle difficult cases through multidisciplinary collaboration, for both surgical management decisions and also follow-up decisions. We summarise current evidence and consider who is at risk, when revision should be undertaken and how patients should be managed.

Keywords: Metal on metal hip; Management; Multi-disciplinary; Revision; Decision

Core tip: Evidence supporting the management of metal on metal hips is lacking, and guidance is open to interpretation. Until supporting evidence is available, an evidence based multi-disciplinary approach on a case-by-case basis is considered a safe method to help surgeons make decisions and potentially improve patient outcomes.