title: Two-stage revision arthroplasty for periprosthetic joint infections: What is the value of cultures and white cell count in synovial fluid and CRP in serum before second stage reimplantation?
abstract: BACKGROUND
  Besides CRP in serum, white cell counts and cultures of synovial fluid are routinely used to detect periprosthetic joint infections. But the sensitivities of these parameters do vary from 12 to 100 %. In two stage revision arthroplasty before the second stage surgeons have to decide if reimplantation is justified. Therefore, we investigated the value of cultures and white cell count from the synovial fluid with a polymethyl methacrylate spacer in place and CRP in serum before reimplantation to detect persistent infection in a standardized setting.
  
  
  METHODS
  115 patients with a two-stage revision hip or knee arthroplasty were included in this study. All patients had an antibiotic loaded polymethylmethacrylate spacer. Retrospectively synovial cultures, white blood count in synovial fluid and CRP in serum were assessed before reimplantation.
  
  
  RESULTS
  The sensitivity of the synovial cultures was 5 % (95 % CI 0.13-24.87), with a specificity of 99 % (95 % CI 94.27-99.97). For white blood count in synovial fluid the sensitivity was 31.3 %, specificity was 39.1 %. Sensitivity for CRP in serum was 42.10 %, specificity was 84.21 %.
  
  
  CONCLUSIONS
  Cultures from synovial fluid and white blood count in synovial fluid and CRP seem to be uncertain parameters to exclude persistent infection. We do not recommend joint aspiration before reimplantation anymore. Further research is necessary to find other markers to confirm or exclude persistent infection.
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany. st.hoell@web.de.
authors.forename: Steffen
authors.initials: S
authors.lastname: Hoell
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Moeller
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Gosheger
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany.
authors.forename: Jendrik
authors.initials: J
authors.lastname: Hardes
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany.
authors.forename: Ralf
authors.initials: R
authors.lastname: Dieckmann
authors.affiliation: Center of Arthroplasty and Revision Arthroplasty, Department of General Orthopedics and Tumor Orthopedics, University Hospital Muenster, Albert Schweitzer Campus 1, 48149, Muenster, Germany.
authors.forename: Dino
authors.initials: D
authors.lastname: Schulz
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000379:methods*; D015415:Biomarkers / Q000097:blood; D002097:C-Reactive Protein / Q000378:metabolism*; D005260:Female; D006801:Humans; D007595:Joint Prosthesis / Q000009:adverse effects*; D007958:Leukocyte Count; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000097:blood / Q000175:diagnosis* / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000166:cytology*
chemical_list: D015415:Biomarkers; D002097:C-Reactive Protein
keywords: Joint aspiration; Periprosthetic joint infection; Spacer; Synovial fluid; Two-stage revision; Value CRP