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We investigated whether blood metal ion levels could effectively identify patients with bilateral Birmingham Hip Resurfacing (BHR) implants who have adverse reactions to metal debris (ARMD).Metal ion levels in whole blood were measured in 185 patients with bilateral BHRs. Patients were divided into those with ARMD who either had undergone a revision for ARMD or had ARMD on imaging (n = 30), and those without ARMD (n = 155). Receiver operating characteristic analysis was used to determine the optimal thresholds of blood metal ion levels for identifying patients with ARMD.The maximum level of cobalt or chromium ions in the blood was the parameter which produced the highest area under the curve (91.0%). The optimal threshold for distinguishing between patients with and without ARMD was 5.5 µg/l (83.3% sensitivity, 88.4% specificity, 58.1% positive and 96.5% negative predictive values). Similar results were obtained in a subgroup of 111 patients who all underwent cross-sectional imaging. Between 3.2% and 4.3% of patients with ARMD were missed if United Kingdom (7 µg/l) and United States (10 µg/l) authority thresholds were used respectively, compared with 2.7% if our implant specific threshold was used, though these differences did not reach statistical significance (p ≥ 0.248).Patients with bilateral BHRs who have blood metal ion levels below our implant specific threshold were at low-risk of having ARMD. Cite this article: Bone Joint J 2016;98-B:1455-62.

Original publication

DOI

10.1302/0301-620x.98b11.38042

Type

Journal article

Journal

The bone & joint journal

Publication Date

11/2016

Volume

98-B

Pages

1455 - 1462

Addresses

The Royal Orthopaedic Hospital, Birmingham B31 2AP, UK and Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford OX3 7LD, UK.

Keywords

Humans, Foreign Bodies, Prosthesis Failure, Chromium, Cobalt, Arthroplasty, Replacement, Hip, Reoperation, Sensitivity and Specificity, Prospective Studies, ROC Curve, Prosthesis Design, Hip Prosthesis, Adult, Aged, Middle Aged, Female, Male, Metal-on-Metal Joint Prostheses, Biomarkers