title: Autoclaved metal-on-cement spacer versus static spacer in two-stage revision in periprosthetic knee infection.
abstract: BACKGROUND
  Periprosthetic knee infection is troublesome for Orthopedic surgeons and a catastrophy for patients. Reported rates of periprosthetic joint infection following primary total knee arthroplasty (TKA) are 0.39-2%. Two stage revision arthroplasty, which has success rates exceeding 90%, has been the gold standard for treating subacute and chronic periprosthetic infection following TKA. Antibiotic spacers, a well established means of delivering local antibiotic therapy, maintain soft tissue tension during two stage revision arthroplasty. However, controversy remains around whether static or mobile antibiotic impregnated spacers are superior for treating infection following TKA. Various mobile spacers are available, including cement-on-cement, cement-on-polyethylene and metal-on-polyethylene. In this study, the efficacy of the modified metal-on-cement spacer, consisting of reinsertion of the autoclaved femoral component and implantation of antibiotic-loaded cement in the proximal tibia, is assessed.
  
  
  METHODS
  Records of 19 patients diagnosed as periprosthetic knee infection were reviewed in this retrospective study. Among these patients, 10 patients received first stage debridement with the autoclaved metal-on-cement spacer and 8 patients with the static spacer, who eventually underwent two-stage re-implantation, were listed in the final comparison. Patient demographics, infection eradication rates, average range of motion (ROM), surgical time and blood loss during the second-stage of the surgery, and Knee Society (KS) knee scores at last followup after revision total knee replacement were clinically evaluated.
  
  
  RESULTS
  At a minimum of 2-year followup after re-implantation, infection eradication rates, surgical times, blood loss during the second-stage of the surgery, and KS knee score after re-implantation were similar for the two groups. Patients receiving autoclaved metal-on-cement spacers had superior ROM after re-implantation compared to that of patients with static spacers.
  
  
  CONCLUSIONS
  The autoclaved metal-on-cement spacer is an effective and simple method for two-stage re-implantation of a periprosthetic knee infection. Through this spacer, the good interim ROM can be achieved without the additional cost of prefabricated molds or new polyethylene tibial inserts. In addition, ROM after re-implantation is better than that with static spacers.
authors.affiliation: Department of Orthopaedic Surgery, Wan Fang Hospital, School of Medicine, Taipei Medial University, Taipei, Taiwan, ROC.
authors.forename: Yu-Pin
authors.initials: YP
authors.lastname: Chen
authors.affiliation: Department of Orthopaedic Surgery, Wan Fang Hospital, School of Medicine, Taipei Medial University, Taipei, Taiwan, ROC.
authors.forename: Cheng-Chun
authors.initials: CC
authors.lastname: Wu
authors.affiliation: Department of Orthopaedic Surgery, Wan Fang Hospital, School of Medicine, Taipei Medial University, Taipei, Taiwan, ROC.
authors.forename: Wei-Pin
authors.initials: WP
authors.lastname: Ho
keywords: Arthroplasty; Mobile spacer; knee; knee joint; knee prosthesis; periprosthetic knee infection; replacement; surgical infection; two-stage re-implantation