Establishing thresholds for metal ion levels in patients with bilateral Articular Surface Replacement hip arthroplasty

Introduction:The primary aim of the current study was to determine whether metal ion levels could identify well- from poorly-functioning implants in patients after undergoing bilateral Articular Surface Replacement (ASR) Hip System. The secondary aim was to establish threshold values for Co and Cr that could be used to predict clinical problems in these patients.Materials and methods:The study included 125 patients treated with bilateral ASR hip resurfacing (HRA) and 93 patients treated with bilateral ASR XL total hip arthroplasty (THA) at a mean follow-up of 7.1 years post-surgery. Patients were labelled as well- or poorly-functioning based on strict criteria. We calculated the Co and Cr safe upper ion limits (SUL) for ASR HRA and ASR XL THA separately and assessed these cutoffs ability to predict clinical problems.Results:In patients with bilateral ASR HRA, the well-functioning group had lower ions than the poorly-functioning. In ASR THA patients, there was no difference in blood Co or Cr levels between...