title: Utility of prerevision tissue biopsy sample to predict revision shoulder arthroplasty culture results in at-risk patients.
abstract: BACKGROUND
  The diagnosis of infection after shoulder arthroplasty can be challenging. The current study evaluated the utility of a prerevision biopsy sample in predicting positive cultures or a final diagnosis of infection in the setting of an "at-risk" failed shoulder arthroplasty.
  
  
  METHODS
  The study reviewed 77 patients with no history of infection undergoing revision shoulder arthroplasty by a single surgeon between June 2010 and July 2015. All patients with a C-reactive protein and erythrocyte sedimentation rate within normal reference ranges and no fluid on aspirate, or an abnormal value for the erythrocyte sedimentation rate or C-reactive protein, or both, and no growth on aspirate, underwent a prerevision biopsy because they were considered "at-risk" for infection. Sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were calculated to evaluate the utility of biopsy specimens to predict positive cultures as well as a final determination of infection.
  
  
  RESULTS
  A prerevision biopsy was performed in 17 patients with a failed arthroplasty. The sensitivity, specificity, PPV, and NPV, for a positive prerevision biopsy sample to predict a positive final culture were 0.75, 0.6, 0.82, and 0.5, respectively. The sensitivity, specificity, PPV, and NPV for an infection defined by a prerevision biopsy sample to predict an infection defined by the combined final revision and biopsy cultures were 0.9, 0.86, 0.9, and 0.86, respectively.
  
  
  CONCLUSIONS
  The ability for prerevision biopsy specimens of failed arthroplasties to predict the presence of bacteria at the time of revision surgery is high, although lower than previously reported. If biopsy results are used to define and predict a diagnosis of infection, the sensitivity, specificity, PPV, and NPV all significantly improve.
authors.affiliation: Department of Orthopaedics, University of Utah School of Medicine, Salt Lake City, UT, USA. Electronic address: Robert.Tashjian@hsc.utah.edu.
authors.forename: Robert Z
authors.initials: RZ
authors.lastname: Tashjian
authors.affiliation: Department of Orthopaedics, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Erin K
authors.initials: EK
authors.lastname: Granger
authors.affiliation: Department of Orthopaedics, University of Utah School of Medicine, Salt Lake City, UT, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001170:Arthritis, Infectious / Q000175:diagnosis* / Q000209:etiology; D000072228:Arthroplasty, Replacement, Shoulder / Q000009:adverse effects*; D001706:Biopsy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000209:etiology; D012086:Reoperation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D012785:Shoulder Joint
keywords: Tissue biopsy; arthroscopic; cultures; infection; revision; shoulder arthroplasty