title: Knee Arthrodesis After Failure of Knee Arthroplasty: A Nationwide Register-Based Study.
abstract: BACKGROUND
  Arthrodesis is considered a salvage procedure after failure of a knee arthroplasty. Data on the use of this procedure are limited. The purpose of this study was to identify the incidence, causes, surgical techniques, and outcomes of arthrodesis after failed knee arthroplasty in a nationwide population.
  
  
  METHODS
  Data were extracted from the Danish Civil Registration System, the Danish National Patient Register, and the Danish Knee Arthroplasty Register. A total of 92,785 primary knee arthroplasties performed in Denmark from 1997 to 2013 were identified by linking the data using the unique personal identification number assigned to each patient. Of these arthroplasties, 165 were followed by arthrodesis. Hospital records of all identified cases of arthrodesis were reviewed. A competing risk model was used to estimate the cumulative incidence of arthrodesis in the study period. Differences in cumulative incidence were compared with the Gray test.
  
  
  RESULTS
  A total of 164 of the 165 arthrodeses were performed for causes related to failed knee arthroplasty. The 15-year cumulative incidence of arthrodesis was 0.26% (95% confidence interval, 0.21% to 0.31%). The 5-year cumulative incidence decreased significantly (p < 0.0001) from 0.32% for arthroplasties performed from 1997 to 2002 to 0.09% for arthroplasties performed from 2008 to 2013. The most common causes of arthrodesis were periprosthetic infection in 152 patients (93%), extensor mechanism disruption in 46 (28%), soft-tissue deficiency in 25 (15%), and severe bone loss in 11 (7%). In 79 patients (48%), there were 2 or more indications for arthrodesis. Solid fusion was achieved in 65% of the patients. The fusion rate was significantly higher after intramedullary nail fixation compared with external fixation (p = 0.01). A total of 34 patients (21%) underwent repeat arthrodesis, and 23 patients (14%) eventually underwent transfemoral amputation.
  
  
  CONCLUSIONS
  The cumulative incidence of arthrodesis within 15 years after primary knee arthroplasty was 0.26%. There was a significant decrease in the 5-year cumulative incidence during the study period, suggesting an overall improvement in prevention of this adverse outcome of knee arthroplasty.
  
  
  METHODS
  Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Orthopedic Surgery, Copenhagen University Hospital Herlev-Gentofte, Hellerup, Denmark tinne.b@hotmail.com.
authors.forename: Tinne B
authors.initials: TB
authors.lastname: Gottfriedsen
authors.affiliation: Department of Orthopedic Surgery, Copenhagen University Hospital Herlev-Gentofte, Hellerup, Denmark Department of Orthopedic Surgery, Naestved Hospital, Naestved, Denmark hemsc@regionsjaelland.dk.
authors.forename: Henrik M
authors.initials: HM
authors.lastname: Schrøder
authors.affiliation: Department of Orthopedic Surgery, Copenhagen University Hospital Herlev-Gentofte, Hellerup, Denmark anders.odgaard@regionh.dk.
authors.forename: Anders
authors.initials: A
authors.lastname: Odgaard
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000601:surgery; D001174:Arthrodesis / Q000379:methods / Q000706:statistics & numerical data*; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D003718:Denmark; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D016459:Prosthesis-Related Infections / Q000209:etiology / Q000601:surgery; D012086:Reoperation; D016896:Treatment Outcome; D055815:Young Adult