The value of serial metal ion levels in following up patients with metal-on-metal hip arthroplasty



The sensitivity of cobalt (Co) and chromium (Cr) ion-levels in detecting poorly performing metal-on-metal hip implants is low. This study proposes that serial changes in ion-levels are a more accurate marker of arthroplasties at risk.


Serial metal ion-levels and implant data of 285 patients with ASR resurfacing or replacement were studied. Patient and implant characteristics were analysed using univariate and multivariate analyses.


111 (39%) had revision surgery. Time since index surgery (p<0.001), acetabular inclination (p<0.001), their interaction (p<0.001) and femoral head size (p = 0.01) were significant variables. Head size (≤51 mm) had lower Co and Cr levels (p = 0.01). Cr/Co showed marginal decrease over time in the unrevised group and no decrease prerevision.


Repeated measurement of ion-levels were higher in the revision group suggesting that serial measurements rather than absolute values may have a role to play in predicting implant failure.

Hip Int 2017; 27(1): 14 - 20




Gavin McHugh, Rajiv Merchant, Gabrielle E. Kelly, Karen M. Bergin, Gerald F. McCoy, Andrew P. Wozniak, John F. Quinlan

Article History


Financial support: None.
Conflict of interest: None.

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  • Lourdes Orthopaedic Hospital, Kilcreene, Kilkenny - Ireland
  • School of Mathematical Sciences, University College Dublin, Dublin - Ireland

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