title: Discrepancies between frozen and paraffin tissue sections have little effect on outcome of staged total knee arthroplasty revision for infection.
abstract: BACKGROUND
  Intraoperative analysis of frozen tissue samples has been used to diagnose periprosthetic joint infection in revision total knee arthroplasty, but the precision and reliability of this test throughout staged revision arthroplasty have not been well characterized. We undertook this study to determine the rate of discrepancy between frozen and permanent histopathologic samples in the diagnosis of periprosthetic infection at both the index total knee arthroplasty revision procedure and the attempted reimplantation.
  
  
  METHODS
  Seventy-six patients who underwent staged revision of a total knee arthroplasty for apparent infection had samples for frozen and permanent sections obtained at both the index revision procedure and subsequent reimplantation attempts. We investigated the rate of discrepancy between these frozen and permanent sections. The clinical and radiographic outcomes of patients with and without concordance between the frozen and permanent sections were reviewed.
  
  
  RESULTS
  Concordance was noted between 297 (97.7%) of the 304 frozen sections and the permanent sections. Seven discrepancies between diagnoses based on frozen and permanent sections were noted; however, additional samples in these patients were positive and management was not affected. Fewer discrepancies were found during the initial revision procedure (one of 92, 1%) compared with reimplantation (six of 212, 3%). The mean time to reimplantation was similar between patients with and without a discrepancy in diagnosis between the frozen and permanent sections (185 compared with 157 days). The rate of discrepancy between frozen and permanent histopathologic sections was low, and no discrepancy affected the final outcome of any patient.
  
  
  CONCLUSIONS
  The rate of discrepancy between frozen and permanent histopathologic samples was low for both index revision and reimplantation procedures. In rare instances of discrepancy, management should be unaffected provided a sufficient number of samples were collected.
authors.affiliation: Center for Joint Preservation and Replacement, Rubin Institute for Advanced Orthopedics, Sinai Hospital of Baltimore, 2401 West Belvedere Avenue, Baltimore, MD 21215, USA. DAStroh@gmail.com
authors.forename: D Alex
authors.initials: DA
authors.lastname: Stroh
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Johnson
authors.forename: Qais
authors.initials: Q
authors.lastname: Naziri
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mont
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods; D015331:Cohort Studies; D020878:Device Removal / Q000379:methods; D005260:Female; D005629:Frozen Sections / Q000379:methods*; D006801:Humans; D007430:Intraoperative Care / Q000379:methods; D008297:Male; D008875:Middle Aged; D016612:Paraffin Embedding / Q000379:methods*; D011183:Postoperative Complications / Q000473:pathology / Q000601:surgery; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000473:pathology* / Q000601:surgery*; D012086:Reoperation / Q000379:methods; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D016896:Treatment Outcome