title: Total knee arthroplasty in patients with hypersensitivity to metals.
abstract: OBJECTIVE
  We evaluated the risk of hypersensitivity to metals in a population of consecutive subjects undergoing a total knee arthroplasty (TKA). We also proposed a diagnostic pathway to address any sensitivity to metals. We finally presented the mid-term outcomes of a full non allergenic knee implant.
  
  
  METHODS
  We developed a protocol based on the medical history, patch testing, and on specific laboratory assays, in order to assess a sensitization to metals. Twenty-four patients (25 knees) with referred or suspected allergy to metals were found in more than 1,000 treated patients, with a mean age of 72.9 years. We proceeded to a radiologic study, a clinical evaluation by the visual analogic scale (VAS), and Knee Society rating system (KSS). In all cases a full anallergic cemented implant with an oxidized zirconium femoral component and an all-polyethylene tibial baseplate was chosen.
  
  
  RESULTS
  Four (16.6%) of the 24 patients were considered to be hypersensitive to metals. The mean follow-up was 79.2 months. No patient reported any reaction related to hypersensitivity or complications after TKA. The VAS improved from a mean preoperative value of 7.2 to 1.8 postoperatively; the KSS and the functional score increased from 38 to 91 points and from 39 to 88 points, respectively.
  
  
  CONCLUSIONS
  We consider careful research of medical history for metals hypersensitivity crucial, and we perform patch testing and lab assays in case of doubtful sensitization. The choice of a modern hypoallergenic implant may prevent any kind of potential reactions.
authors.affiliation: First Orthopaedic Clinic, University of Florence, Florence, Italy.
authors.forename: Massimo
authors.initials: M
authors.lastname: Innocenti
authors.forename: Christian
authors.initials: C
authors.lastname: Carulli
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Matassi
authors.forename: Anna Maria
authors.initials: AM
authors.lastname: Carossino
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Brandi
authors.forename: Roberto
authors.initials: R
authors.lastname: Civinini
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology*; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008670:Metals / Q000009:adverse effects*; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D020959:Polyethylene; D015995:Prevalence; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D015040:Zirconium / Q000009:adverse effects
chemical_list: D008670:Metals; D020959:Polyethylene; D015040:Zirconium