title: Use of erythrocyte sedimentation rate and C-reactive protein level to diagnose infection before revision total knee arthroplasty. A prospective evaluation.
abstract: BACKGROUND
  Despite the widespread use of several diagnostic tests, there is still no perfect test for the diagnosis of infection at the site of a total knee arthroplasty. The purpose of this study was to evaluate the diagnostic test characteristics of the erythrocyte sedimentation rate and C-reactive protein level for the assessment of infection in patients presenting for revision total knee arthroplasty.
  
  
  METHODS
  One hundred and fifty-one knees in 145 patients presenting for revision total knee arthroplasty were evaluated prospectively for the presence of infection with measurement of the erythrocyte sedimentation rate and the C-reactive protein level. The characteristics of these tests were assessed with use of two different techniques: first, receiver-operating-characteristic curve analysis was performed to determine the optimal positivity criterion for the diagnostic test, and, second, previously accepted criteria for establishing positivity of the tests were used.
  
  
  RESULTS
  A diagnosis of infection was established for forty-five of the 151 knees that underwent revision total knee arthroplasty. The receiver-operating-characteristic curves indicated that the optimal positivity criterion was 22.5 mm/hr for the erythrocyte sedimentation rate and 13.5 mg/L for the C-reactive protein level. Both the erythrocyte sedimentation rate (sensitivity, 0.93; specificity, 0.83; positive likelihood ratio, 5.81; accuracy, 0.86) and the C-reactive protein level (sensitivity, 0.91; specificity, 0.86; positive likelihood ratio, 6.89; accuracy, 0.88) have excellent diagnostic test performance.
  
  
  CONCLUSIONS
  The erythrocyte sedimentation rate and the C-reactive protein level provide excellent diagnostic test information for establishing the presence or absence of infection prior to surgical intervention in patients with pain at the site of a knee arthroplasty.
authors.affiliation: Department of Orthopaedics, University of British Columbia, Laurel Pavilion, 910 West 10th Avenue, Vancouver, BC V5Z 4E3, Canada. nelson.greidanus@vch.ca
authors.forename: Nelson V
authors.initials: NV
authors.lastname: Greidanus
authors.forename: Bassam A
authors.initials: BA
authors.lastname: Masri
authors.forename: Donald S
authors.initials: DS
authors.lastname: Garbuz
authors.forename: S Darrin
authors.initials: SD
authors.lastname: Wilson
authors.forename: M Gavan
authors.initials: MG
authors.lastname: McAlinden
authors.forename: Min
authors.initials: M
authors.lastname: Xu
authors.forename: Clive P
authors.initials: CP
authors.lastname: Duncan
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000032:analysis*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D011300:Preoperative Care; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000097:blood / Q000175:diagnosis* / Q000188:drug therapy; D012372:ROC Curve; D012086:Reoperation; D012680:Sensitivity and Specificity
chemical_list: D002097:C-Reactive Protein