title: Minimizing dynamic knee spacer complications in infected revision arthroplasty.
abstract: BACKGROUND
  Deep infections are devastating complications of TKA often treated with component explantation, intravenous antibiotics, and antibiotic-impregnated cement spacers. Historically, the spacers have been static, which may limit patients' ROM and ability to walk. Several recent reports describe dynamic spacers, which may allow for improved ROM and make later reimplantation easier. However, because of several dynamic spacer problems noted at our institution, we wanted to assess their associated failures, reinfection rates, and functionality.
  
  
  OBJECTIVE
  We therefore asked whether there were differences between static and dynamic spacers in (1) reinfection rates, (2) complications directly related to the spacer, and (3) final patient functionality as measured by Knee Society objective scores and ROM.
  
  
  METHODS
  We retrospectively identified 111 patients (115 knees) with 34 dynamic spacers (30%) and 81 static spacers (70%). Reinfection rates, complications requiring additional surgery, and final Knee Society scores and ROM were collected for all patients.
  
  
  RESULTS
  Reinfection rates were comparable between groups. In the dynamic spacer cohort, there were four complications; however, these could all be explained by surgical technical errors or patient weightbearing compliance. All patients with failed results eventually underwent successful two-stage exchange arthroplasty. Final Knee Society scores and ROM were also similar between groups.
  
  
  CONCLUSIONS
  Reinfection rates, Knee Society scores, and ROM were comparable between the static and dynamic spacer groups. Meticulous surgical technique and proper patient selection should be used to avoid any complications with any spacers.
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.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Johnson
authors.forename: Siraj A
authors.initials: SA
authors.lastname: Sayeed
authors.forename: Qais
authors.initials: Q
authors.lastname: Naziri
authors.forename: Harpal S
authors.initials: HS
authors.lastname: Khanuja
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mont
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000295:instrumentation* / Q000379:methods; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010149:Postoperative Pain / Q000209:etiology / Q000503:physiopathology / Q000517:prevention & control; D011474:Prosthesis Design; D016459:Prosthesis-Related Infections / Q000000981:diagnostic imaging / Q000209:etiology / Q000601:surgery*; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D020127:Recovery of Function; D012086:Reoperation / Q000379:methods*; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome