title: α-Defensin Accuracy to Diagnose Periprosthetic Joint Infection-Best Available Test?
abstract: BACKGROUND
  The purpose of this study was to test the accuracy of a single synovial fluid biomarker, α-defensin, in diagnosing periprosthetic joint infection in revision total hip and revision total knee arthroplasty.
  
  
  METHODS
  A total of 102 patients comprising 116 revision total hip arthroplasty and revision total knee arthroplasty procedures performed between May 2013 and March 2014 were prospectively evaluated. Cases were categorized as infected or notinfected using Musculoskeletal Infection Society criteria. Synovial fluid was obtained and tested for α-defensin using a commercially available kit (Synovasure [CD Diagnostics, Baltimore, Maryland]).
  
  
  RESULTS
  For first-stage and single-stage revisions, the α-defensin test had a sensitivity of 100% (95% confidence interval [CI], 86%-100%) and a specificity of 98% (95% CI, 90%-100%) with a positive predictive value of 96% (95% CI, 80%-99%) and negative predictive value of 100% (95% CI, 93%-100%).
  
  
  CONCLUSIONS
  A positive α-defensin test result was significantly more sensitive and specific for predicting infection than current diagnostic testing and should be considered when managing periprosthetic joint infection.
  
  
  METHODS
  Level III, Study of Diagnostic Test.
authors.affiliation: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Salvatore J
authors.initials: SJ
authors.lastname: Frangiamore
authors.affiliation: Lerner College of Medicine, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Gajewski
authors.affiliation: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Anas
authors.initials: A
authors.lastname: Saleh
authors.affiliation: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Mario
authors.initials: M
authors.lastname: Farias-Kovac
authors.affiliation: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Wael K
authors.initials: WK
authors.lastname: Barsoum
authors.affiliation: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, Ohio.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Higuera
mesh_terms: D000368:Aged; D001170:Arthritis, Infectious / Q000175:diagnosis; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D015415:Biomarkers / Q000032:analysis; D002097:C-Reactive Protein / Q000032:analysis; D003955:Diagnostic Tests, Routine; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis*; D012086:Reoperation; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000737:chemistry; D023084:alpha-Defensins / Q000032:analysis*
chemical_list: D015415:Biomarkers; D023084:alpha-Defensins; D002097:C-Reactive Protein
keywords: hip and knee infection; infection biomarker; periprosthetic joint infection; synovial fluid; α-defensin