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601 metal-on-metal total hip replacements with 36 mm heads a 5 minimum year follow up: Levels of ARMD remain low despite a comprehensive screening program

Atrey, A; Hart, A; Hussain, N; Waite, J; Shepherd, AJ; Young, S; (2017) 601 metal-on-metal total hip replacements with 36 mm heads a 5 minimum year follow up: Levels of ARMD remain low despite a comprehensive screening program. Journal of Orthopaedics , 14 (1) pp. 108-114. 10.1016/j.jor.2016.10.023. Green open access

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Abstract

BACKGROUND: We conducted a retrospective study to assess the clinical outcome, failure rate, and reason for failure of a large consecutive series of 36 mm MoM Corail/Pinnacle total hip replacements (THRs). METHODS: Between 2006 and 2011, 601 consecutive 36 mm MoM THRs were performed (585 patients). Patients were followed according to the UK Medicines and Healthcare Products Regulatory Agency (MHRA) guidelines. All patients were accounted for and 469 patients (78%) were clinically and radiographically assessed. 328 females and 141 males with a median age of 73 (range 36-94 years) and a median follow up of 7.2 years (range 5.2-9.7 years) were followed. Clinical data included blood cobalt and chromium, Oxford Hip Score (OHS), plain radiograph, ultrasound of hip and intra-operative findings in those patients who had revision surgery. RESULTS: 56 patients died of causes unrelated to their hip replacement. The mean survivorship of the implant was 92.8% (range 91.6-94%, 95% CI) at a median time to follow up of 84 months (62-113 months). The functional outcome was good with a median OHS of 38 out of 48 (23-44). The dislocation rate was 0.99%, with all these 6 cases requiring revision. 476 patients had blood tests. 100 patients (21%) had elevated levels of either cobalt above MHRA guidelines of 7 parts per billion (120 and 135 nmol/L respectively for cobalt and chromium). Cobalt was elevated independently of chromium in 75% of the cases (but never vice versa). The mean cup inclination angle was 42°. Each incremental stem size increase resulted in a decrease in cobalt by 11 nmol/L. The most common reason for revision was adverse reaction to metal debris (ARMD) (12 cases). CONCLUSION: This paper is the largest and longest follow up of 36 mm MoM THRs. Using the MHRA guidelines for follow up, the revision rates of this cohort has remained low compared to other studies, but unacceptably higher than that of other bearing surfaces. LEVEL OF EVIDENCE: III.

Type: Article
Title: 601 metal-on-metal total hip replacements with 36 mm heads a 5 minimum year follow up: Levels of ARMD remain low despite a comprehensive screening program
Location: India
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jor.2016.10.023
Publisher version: https://doi.org/10.1016/j.jor.2016.10.023
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: ARMD, Corail/Pinnacle, Failure, MoM, Revision, Survivorship, Taper corrosion, Trunnionosis
UCL classification: UCL
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci
UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Medical Sciences > Div of Surgery and Interventional Sci > Department of Ortho and MSK Science
URI: https://discovery.ucl.ac.uk/id/eprint/10042565
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