title: α-Defensin as a predictor of periprosthetic shoulder infection.
abstract: BACKGROUND
  Diagnosis of periprosthetic joint infection (PJI) in revision shoulder arthroplasty can be challenging because of the indolent nature of the common offending organisms. The purpose of this study was to evaluate the diagnostic utility of synovial fluid α-defensin levels in identifying PJI of the shoulder.
  
  
  METHODS
  Thirty patients evaluated for painful shoulder arthroplasty were prospectively enrolled and underwent revision surgery (n = 33 cases). Cases were categorized into infection (n = 11) and no-infection (n = 22) groups on the basis of preoperative and intraoperative findings. Synovial fluid was obtained from preoperative aspirations or intraoperative aspiration before arthrotomy. α-Defensin was tested by the Synovasure (CD Diagnostics, Wynnewood, PA, USA) test for joint infection. Synovial fluid was also obtained intraoperatively from a control group undergoing arthroscopic rotator cuff repair (n = 16) for baseline data on normal α-defensin levels in the shoulder. A receiver operating characteristic curve was used to determine the diagnostic utility of synovial fluid α-defensin.
  
  
  RESULTS
  Synovial α-defensin had an area under the curve, sensitivity, specificity, and positive and negative likelihood ratios of 0.78, 63%, 95%, 12.1, and 0.38, respectively. There was a significant difference in α-defensin levels between the infection (median, 3.2 S/CO [signal to cutoff ratio]) and no-infection groups (median, 0.21 S/CO; P = .006). Synovial α-defensin was elevated in the presence of a culture positive for Propionibacterium acnes (median, 1.33 S/CO; P = .03) and showed moderate correlation with the number of positive cultures.
  
  
  CONCLUSIONS
  Synovial fluid α-defensin was more effective than current diagnostic testing in predicting positive cultures and may be an effective adjunct in the workup of shoulder PJI.
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Salvatore J
authors: SJ
authors: Frangiamore
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Anas
authors: A
authors: Saleh
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Matthew J
authors: MJ
authors: Grosso
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Mario Farias
authors: MF
authors: Kovac
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Carlos A
authors: CA
authors: Higuera
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA.
authors: Joseph P
authors: JP
authors: Iannotti
authors: Department of Orthopedic Surgery, The Cleveland Clinic Foundation, Cleveland, OH, USA. Electronic address: ricchee@ccf.org.
authors: Eric T
authors: ET
authors: Ricchetti
mesh_terms: D019643:Arthroplasty, Replacement; D015415:Biomarkers / Q000378:metabolism; D005260:Female; D006801:Humans; D016013:Likelihood Functions; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D012785:Shoulder Joint / Q000382:microbiology / Q000601:surgery*; D013582:Synovial Fluid / Q000378:metabolism*; D023084:alpha-Defensins / Q000378:metabolism*
chemical_list: D015415:Biomarkers; D023084:alpha-Defensins
keywords: P. acnes; periprosthetic joint infection; shoulder arthroplasty; shoulder infection; synovial fluid; α-Defensin