Are dual mobility cups associated with increased metal ions in the blood? Clinical study of nickel and chromium levels with 29 months’ follow-up

Dual mobility cups have become the implant of choice for older patients with a high risk of dislocation. However, to our knowledge, no study has explored the possibility of metal ion production with these implants that incorporate a polyethylene-on-metal bearing. This led us to conduct a prospective study to determine whether use of a dual mobility cup is accompanied by increased levels of nickel and chromium in the blood. Use of a dual mobility cup is accompanied by an increase of nickel and chromium levels in the blood. Between 2012 and 2015, 16 consecutive patients were enrolled in the study. They underwent primary hip arthroplasty with a ceramic Biolox™ head (CeramTec, Plochingen, Germany), Corail™ titanium alloy stem (DePuy Synthes, Saint Priest, France) and a Novae™ dual mobility cup (SERF, Décines-Charpieu, France) consisting of 19% chromium (Cr) and 13–15% nickel (Ni). Patients who had other potential sources of nickel or chromium in their body (joint implants, dental implants, etc.) were excluded. The blood levels (μg/L) of nickel and chromium were measured preoperatively and at 2 years’ follow-up by an independent laboratory (Biomnis) using inductively coupled plasma mass spectrometry. The upper limits set by the laboratory were1μg/L) and the chromium ion levels averaged 0.5±0.11 [0.4–0.7] (with no patients>0.7μg/L). There were no signs of loosening or osteolysis on the follow-up radiographs. The mean PMA score at 2 years was 17.8 [17,18]. We found that dual mobility cups generate increased nickel but not chromium ions in the blood. The levels measured are comparable to those for other orthopedic implants such as spine implants. The clinical con