title: Sonication of antibiotic spacers predicts failure during two-stage revision for prosthetic knee and hip infections.
abstract: BACKGROUND
  Periprosthetic joint infection is a leading cause of failure after two-stage reimplantation. One cause of relapse may be persistent subclinical infection. Difficulty exists in detecting biofilm-forming infections. Sonication disrupts biofilm and has led to higher rates of positive intraoperative cultures.
  
  
  OBJECTIVE
  Our aims in this study were to determine (1) if sonication results were predictive of failure, including reinfection, at 2-year followup; and (2) whether sonication of antibiotic spacers at the time of reimplantation improves sensitivity of intraoperative cultures.
  
  
  METHODS
  We prospectively followed 36 consecutive patients undergoing two-stage reimplantation for periprosthetic hip or knee infection. Minimum followup was 19 months (mean, 29.9 months; range, 19–38 months). Results of intraoperative cultures and sonicated antibiotic spacers were analyzed.
  
  
  RESULTS
  Positive sonication results were predictive of failure as defined by reinfection at 2-year followup. Among the 18 patients who had positive sonication results, reinfection developed in nine patients (50%) compared with two of 18 patients (11%) with negative sonication results (odds ratio, 8.0; 95% CI, 1.2–69.0). Sonication of antibiotic spacers improved the sensitivity of intraoperative cultures from 45% to 82%. [corrected].
  
  
  CONCLUSIONS
  Sonication of antibiotic spacers appears to be useful in predicting failure attributable to recurrent infection after two-stage reimplantation. For patients with positive sonication cultures during reimplantation, more aggressive antimicrobial treatment may be indicated after reimplantation.
  
  
  METHODS
  Level III, diagnostic study. See the Instructions for Authors for a complete description of levels of evidence.
authors.forename: Charles L
authors.initials: CL
authors.lastname: Nelson
authors.forename: Robert B
authors.initials: RB
authors.lastname: Jones
authors.forename: Nathaniel C
authors.initials: NC
authors.lastname: Wingert
authors.forename: Michael
authors.initials: M
authors.lastname: Foltzer
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Bowen
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000900:Anti-Bacterial Agents / Q000008:administration & dosage*; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000295:instrumentation*; D001431:Bacteriological Techniques; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development; D001843:Bone Cements / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D006622:Hip Prosthesis / Q000009:adverse effects* / Q000382:microbiology; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects* / Q000382:microbiology; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011474:Prosthesis Design; D016459:Prosthesis-Related Infections / Q000175:diagnosis / Q000382:microbiology / Q000601:surgery*; D012008:Recurrence; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013010:Sonication; D013997:Time Factors; D017211:Treatment Failure; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D001843:Bone Cements