Out of joint: The story of the ASRBMJ 2011; 342 doi: https://doi.org/10.1136/bmj.d2905 (Published 14 May 2011) Cite this as: BMJ 2011;342:d2905
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We were pleased to read the very timely review of the controversy regarding the Articular Surface Replacement (ASR) metal-on-metal hip resurfacing arthroplasty in the BMJ  and not an Orthopaedic Journal. Metal-on-metal bearings have become ever more popular over the last decade and are now present in many patients who present to their General Practitioners for other reasons. Whilst working at The Royal National Orthopaedic Hospital, Stanmore we had the benefit of seeing many patients with interesting complications from their metal bearing prostheses.
It became apparent that unfortunately, many of the patients that we were seeing had had a very convoluted route to get to the correct specialist hospital. Many patients were not suffering pain around their hip but instead had both central and peripheral neuropathies. The mechanism behind neuropathy is poorly understood but may be due to direct neurotoxicity, pressure effects of wear debris or related to hypersensitivity reactions [2,3,4] . These patients were often referred to us via our local Neurologists after extensive investigations taking many weeks/months.
Delays in presentation undoubtedly lead to a poorer outcome. These delays have led us to develop a simple diagnostic triad to help recognise the metal-on-metal bearing as a possible causative factor to the unexplained neurological pathology.
This triad consists of:
* Unexplained neurology
* Elevated serum cobalt and/or chromium ion levels
* The presence of a metal bearing hip
If all 3 factors are present then urgent referral to a specialist Orthopaedic Surgeon is warranted for further investigation and consideration of exchange arthroplasty.
Out of joint: The story of the ASR. Cohen D. BMJ. 2011 May 13;342:d2905. doi: 10.1136/bmj.d2905 Willert HG, Buchhorn GH, Fayyazi A, Flury R, Windler M, K?ster G, Lohmann CH. Metal on metal bearings and hypersensitivity in patients with artificial hip joints. A clinical and histomorphological study. J Bone Joint Surg (Am). 2005;87:28-36 Langton DJ, Jameson SS, Joyce TJ, Hallab NJ, Natu S, Nargol AV. Early failure of metal-on-metal bearings in hip resurfacing and large-diameter total hip replacement: A consequence of excess wear. J Bone Joint Surg Br. 2010 Jan;92(1):38-46 Keegan GM, Learmonth ID, Case CP. A systematic comparison of the actual, potential, and theoretical health effects of cobalt and chromium exposures from industry and surgical implants. Crit Rev Toxicol. 2008;38(8):645-674
Competing interests: None declared