title: Diagnostic accuracy of arthroscopic biopsy in periprosthetic infections of the hip.
abstract: BACKGROUND
  Diagnosis of a low-grade periprosthetic joint infection (PJI) prior to revision surgery can be challenging, despite paramount importance for further treatment. Arthroscopic biopsy of synovial and periprosthetic tissue with subsequent microbiological and histological examination can be beneficial but its specific diagnostic value has not been clearly defined.
  
  
  METHODS
  20 consecutive patients who underwent percutaneous synovial fluid aspiration as well as arthroscopic biopsy due to suspected PJI of the hip and subsequent one- or two-stage revision surgery at our institution between January 2012 and May 2015 were enrolled. Indication was based on the criteria (1) history of PJI and increased levels of erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP), (2) suspicious cell count and differential but negative bacterial culture in synovial aspirate, (3) early loosening (<less than 2 years), or (4) persisting pain without loosening but history of a PJI. At least two criteria had to be fulfilled in order to perform an arthroscopic biopsy.
  
  
  RESULTS
  Best overall diagnostic value was identified for arthroscopic biopsy and a combination of bacteriological and histological analysis with a sensitivity of 87.5%, specificity of 100% and accuracy of 95%. Bacteriological assessment of synovial aspirate revealed a sensitivity of 50.0%, specificity of 91.7%, and accuracy of 75%. ESR and CRP yielded a sensitivity of 75.0% for either hematologic test and specificities of 87.5 and 66.7%, respectively.
  
  
  CONCLUSIONS
  In conclusion, our data indicate that arthroscopic biopsy is superior to ESR and CRP as well as joint aspiration and their combinations. Concurrent microbiological and histological examination of the biopsy specimens allows for identification of the causative pathogen and its susceptibility pattern in order to preoperatively plan the surgical strategy as well as the antibiotic regimen. Moreover, intraarticular mechanical failure can be detected during hip arthroscopy emphasizing its diagnostic value. Level II diagnostic study.
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany. florian.pohlig@mri.tum.de.
authors.forename: Florian
authors.identifier: http://orcid.org/0000-0002-8867-2973
authors.initials: F
authors.lastname: Pohlig
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Heinrich M L
authors.initials: HM
authors.lastname: Mühlhofer
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Lenze
authors.affiliation: Department of Traumatology, Klinikum Traunstein, Cuno-Niggl-Str. 3, 83278, Traunstein, Germany.
authors.forename: Florian W
authors.initials: FW
authors.lastname: Lenze
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Suren
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Norbert
authors.initials: N
authors.lastname: Harrasser
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: von Eisenhart-Rothe
authors.affiliation: Department of Orthopedic Surgery, Klinikum rechts der Isar, Technical University Munich, Ismaninger Str. 22, 81675, Munich, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schauwecker
mesh_terms: D019644:Arthroplasty, Replacement, Hip; D001182:Arthroscopy; D001706:Biopsy; D001799:Blood Sedimentation; D002097:C-Reactive Protein / Q000737:chemistry; D006801:Humans; D010003:Osteoarthritis / Q000150:complications / Q000601:surgery; D016459:Prosthesis-Related Infections / Q000175:diagnosis* / Q000382:microbiology*; D012086:Reoperation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013582:Synovial Fluid / Q000382:microbiology*; D013583:Synovial Membrane / Q000503:physiopathology; D016896:Treatment Outcome
chemical_list: D002097:C-Reactive Protein
keywords: Aspiration; Biopsy; Hip arthroscopy; PJI; Periprosthetic infection; Revision hip arthroplasty