Asymptomatic intraprosthetic dual mobility cup dislocation with increased metal ion levels

Abstract

With the increased use of dual-mobility cups (DMCs) in total-and revision hip arthroplasties, surgeons can expect an increase of known and new complications. During routine follow-up, we observed an asymptomatic patient with an intraprosthetic-dislocation (IPD) and elevated levels of serum metal ions (1.8 ppb of cobalt and 28.0 ppb of chromium). Revision surgery was inevitable. Perioperative metallosis and severe wear of the metal shell and metal femoral head supported the IPD. Literature showed that the modularity of the DMC can result in increased serum metal ions, create excessive wear, and possibly affect implant survival. Our case and review of the literature may form an argument not to consider DMC for primary cases. Furthermore, we advise yearly clinical and radiological follow-up and, on indication, metal ion testing for DMCs. Keywords: Dual mobility cup, Revision surgery, Metal ions, Total hip arthroplasty, Intraprosthetic dislocation