title: Two-stage exchange arthroplasty for infected total knee arthroplasty: predictors of failure.
abstract: BACKGROUND
  In North America, a two-stage exchange arthroplasty remains the preferred surgical treatment for chronic periprosthetic joint infection (PJI). Currently, there are no proper indicators that can guide orthopaedic surgeons in patient selection for two-stage exchange or the appropriate conditions in which to reimplant.
  
  
  OBJECTIVE
  To identify (1) the rate of recurrent PJI after two-stage exchange and (2) the role of 15 presurgical and 11 operative factors in influencing the outcome of two-stage revision.
  
  
  METHODS
  From a prospective database we identified 117 patients who had undergone two-stage exchange arthroplasty for PJI of the knee from 1997 to 2007. Failure of two-stage revision was defined as any treated knee requiring further treatment for PJI. We identified 15 presurgical and 11 surgical factors that might be related to failure. Minimum followup was 2 years (average, 3.4 years; range, 2-9.4 years).
  
  
  RESULTS
  Thirty-three of 117 reimplantations (28%) required reoperation for infection. Age, gender, body mass index, and comorbidity indices were similar in both groups. Multivariate analysis provided culture-negative (odds ratio [OR], 4.5; 95% confidence interval [CI], 1.3-15.7), methicillin-resistant organisms (OR, 2.8; 95% CI, 0.8-10.3), and increased reimplantation operative time (OR, 1.01; 95% CI, 1.0-1.03) as predictors of failure. ESR and CRP values at the time of reimplantation and time from resection to reimplantation were not predictors.
  
  
  CONCLUSIONS
  Our observations suggest the failure rate after two-stage reimplantation for infected TKA is relatively high. Culture-negative or methicillin-resistant PJI increases the risk of failure over four- and twofold, respectively. We identified no variables that would guide the surgeon in identifying acceptable circumstances in which to perform the second stage.
  
  
  METHODS
  Level III, prognostic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: The Rothman Institute of Orthopaedics at Thomas Jefferson University Hospital, 925 Chestnut Street, 5th Floor, Philadelphia, PA 19107, USA.
authors.forename: S M Javad
authors.initials: SM
authors.lastname: Mortazavi
authors.forename: David
authors.initials: D
authors.lastname: Vegari
authors.forename: Anthony
authors.initials: A
authors.lastname: Ho
authors.forename: Benjamin
authors.initials: B
authors.lastname: Zmistowski
authors.forename: Javad
authors.initials: J
authors.lastname: Parvizi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000379:methods*; D001843:Bone Cements / Q000494:pharmacology; D002908:Chronic Disease; D016208:Databases, Factual; D005260:Female; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D016106:Methicillin Resistance / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D018579:Patient Selection; D011237:Predictive Value of Tests; D011446:Prospective Studies; D016459:Prosthesis-Related Infections / Q000209:etiology* / Q000382:microbiology / Q000601:surgery*; D012086:Reoperation; D017211:Treatment Failure
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements