title: Corrosion at the cone/taper interface leads to failure of large-diameter metal-on-metal total hip arthroplasties.
abstract: BACKGROUND
  Metal-on-metal (MoM) THAs have reduced wear rates compared with metal-on-polyethylene. However, elevated serum metal ion levels and pseudotumors have been reported in large MoM articulations.
  
  
  OBJECTIVE
  We therefore determined (1) if corrosion occurred at the cone/taper interface leading to instability in patients with large-diameter THAs; (2) how patients presented clinically and radiographically; (3) if adverse periprosthetic tissue reactions occurred; (4) whether metal was released from the implants into the periprosthetic tissues; and (5) if head size correlated with metal release.
  
  
  METHODS
  We reviewed 114 patients who had revisions of large-diameter head MoM articulations. Mean time of implantation was 46 months. To identify adverse reactions and particle load, tissues were stained by hematoxylin and eosin and CD3/CD20/CD68 antibodies. Periprosthetic tissues were analyzed for metal content and distribution in different regions. Electrochemical reactions between the stem and adapter were investigated by a minicell electrode.
  
  
  RESULTS
  Electrochemical studies on the stem and the head adapter showed a risk for galvanic corrosion. Ninety-four percent of patients had instability at the cone/taper interface. All patients presented with early clinical symptoms; 59 patients had radiographic signs of loosening. One hundred four patients had foreign body reactions and necrosis. The largest amounts of metal released were titanium or iron. We found no correlation between head size and metal ion release.
  
  
  CONCLUSIONS
  These findings suggest that in modular cone/taper connections, friction of the MoM articulations may cause failure of the cone/taper interface leading to galvanic corrosion and loosening. It is unclear whether the design of this MoM system provides sufficient stability at the taper.
authors.affiliation: Department of Orthopaedics, Otto-von-Guericke University, Leipziger Str 44, 39108 Magdeburg, Germany.
authors.forename: Heiko
authors.initials: H
authors.lastname: Meyer
authors.forename: Tina
authors.initials: T
authors.lastname: Mueller
authors.forename: Gesine
authors.initials: G
authors.lastname: Goldau
authors.forename: Kathrin
authors.initials: K
authors.lastname: Chamaon
authors.forename: Marcel
authors.initials: M
authors.lastname: Ruetschi
authors.forename: Christoph H
authors.initials: CH
authors.lastname: Lohmann
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D001672:Biocompatible Materials; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D007593:Joint Instability / Q000209:etiology* / Q000601:surgery; D008297:Male; D008670:Metals / Q000009:adverse effects / Q000032:analysis; D008875:Middle Aged; D011475:Prosthesis Failure; D011859:Radiography; D012189:Retrospective Studies
chemical_list: D001672:Biocompatible Materials; D008670:Metals