• A Moroni, L Savarino, M Hoque, M Cadossi, and N Baldini.
• Department II of Orthopaedics and Traumatology, Bologna University, Rizzoli Orthopaedic Institute, Via G C Pupilli 1, 40136 Bologna, Italy. a.moroni@ior.it
• Clin. Orthop. Relat. Res. 2011 Jan 1;469(1):180-7.

BackgroundMetal-on-metal Birmingham hip resurfacing (MOM-BHR) is an alternative to metal-on-metal total hip arthroplasty (MOM-THA), especially for young and/or active patients. However, wear resulting in increased serum ion levels is a concern.Questions/PurposesWe asked whether (1) serum chromium (Cr), cobalt (Co), and molybdenum (Mo) concentrations would differ between patients with either MOM-BHR or MOM-THA at 5 years, (2) confounding factors such as gender would influence ion levels; and (3) ion levels would differ at 2 and 5 years for each implant type.Patients And MethodsIons were measured in two groups with either MOM-BHR (n = 20) or MOM-THA (n = 35) and a mean 5-year followup, and two groups with either MOM-BHR (n = 15) or MOM-THA (n = 25) and a mean 2-year followup. Forty-eight healthy blood donors were recruited for reference values.ResultsAt 5 years, there were no differences in ion levels between patients with MOM-BHR or MOM-THA. Gender was a confounding factor, and in the MOM-BHR group at 5 years, Cr concentrations were greater in females compared with those of males. Mean ion levels were similar in patients with 2 and 5 years of followup for each implant type. Ion levels in patients were sevenfold to 10-fold higher than in controls.ConclusionsAs the metal ion concentrations in the serum at 5 years were in the range reported in the literature, we do not believe concerns regarding excessive metal ion levels after MOM-BHR are justified.Level Of EvidenceLevel III, therapeutic study. See the Guidelines for Authors for a complete description of level of evidence.

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