The effect of a manufacturer recall on the threshold to revise a metal-on-metal hip

Abstract

Management of the unexplained, painful large diameter metal-on-metal (MOM) hip replacement is difficult. Although there are guidelines for surgeons, there is no clear documented evidence describing the overall threshold for revision surgery. The 2010 product recall of the DePuy Articular Surface Replacement (ASR) and subsequent media coverage may have increased patient and surgeon apprehension, resulting in earlier intervention, i.e. at a greater Oxford hip score (OHS) than expected. Our aim was to investigate whether the threshold for revision using known parameters was affected by the ASR recall. These parameters include poor clinical results (persistent pain or mechanical symptoms), pseudotumour or other progressive soft tissue involvement, osteolysis and high or rising metal ion levels. We used our national referral database of MOM hips, which were revised between 2008 and 2012. Once inclusion and exclusion criteria were applied, we identified 240 patients--71 patients in the pre-recall group and 169 patients in the post-recall group. The ASR product recall did not seem to affect the threshold for revision of a MOM hip, with no significant difference between the two groups in terms of the functional (median OHS = 17 pre-recall and 20 post-recall; p = 0.2109) and radiological (median inclination angle = 50 pre-recall and 48 post-recall; p = 0.3221) markers used to guide management. We did however discover that blood metal ion levels were higher in the post-recall group. Issue of a product recall did not change the hip function threshold for revision surgery. The decision to revise a metal-on-metal hip is complex and should follow published guidelines, encompassing metal ion measurement and cross-sectional imaging where appropriate.