Equally low blood metal ion levels at 10-years follow up of total hip arthroplasties with Oxinium, CoCrMo and stainless steel femoral heads. Data from a randomized clinical trial

Background and purposeThe use of inert head materials such as ceramic heads has been proposed as a method of reducing wear and corrosion products from the articulating surfaces in total hip arthroplasty (THA), as well as from the stem-head taper connection. In the present study, we wanted to evaluate the blood metal ion levels of Oxinium modular femoral heads at 10 years postoperatively and compare with the CoCrMo modular femoral head counterpart, and the monoblock stainless steel Charnley prosthesis. Patients and methods150 patients with osteoarthritis of the hip joint previously included in a randomized clinical trial that had the primary aim of examining polyethylene wear in cemented THAs were re-grouped according to femoral head material. One group (n=30) had received the Charnley monoblock stainless steel stem with 22.2 mm head (DePuy, UK). The other groups (n=120) received a Spectron EF CoCrMo stem with either a 28 mm CoCrMo or Oxinium modular head (Smith & Nephew, USA). After 10 years, 19 patients had died and 38 withdraw from the study. Five patients were revised due to infection in their hip and 7 were revised due to aseptic loosening of either the cup or stem or both. 81 patients with median age of 79 years (70-91) were available for whole blood metal ion analysis. ResultsThe levels of Co, Cr, Ni and Zr in the blood were generally low with all head materials (medians <0.3 micrograms/L). We found no statistically significant difference in the concentration of metal ions between the group with Charnley prosthesis (n=17) and those with Spectron EF stems with either CoCrMo (n=32) or Oxinium heads (n=32) (p=0.18-0.81). InterpretationIn this study of patients with non-revised THAs, no indication of severe trunnion corrosion was found. The blood ion levels with the use of ceramic Oxinium modular femoral heads were similar to CoCrMo or stainless steel heads at 10 years follow-up.