title: Midterm assessment of causes and results of revision total knee arthroplasty.
abstract: BACKGROUND
  There is limited information regarding revision total knee arthroplasty (TKA) with respect to etiology, outcome, and long-term survival comparing different implant types.
  
  
  OBJECTIVE
  We compared patient outcomes, survivorship and modes of failure and the most common etiologic factors for rerevision between different revision implant types.
  
  
  METHODS
  We retrospectively reviewed 349 cases of revision TKA in 343 patients whose mean age was 67.8 years. Three implant types were used: posterior stabilized, condylar constrained knee, and rotating hinge. The etiologies included infection (32.7%), aseptic loosening (14.9%), and polyethylene wear (12.3%). The minimum followup was 12 months (mean, 57.7 months; range, 12-120 months).
  
  
  RESULTS
  The mean Knee Society scores were 89 (range, 48-94), 88.9 (range, 45-95), and 84 (range, 56-94) and the mean ranges of motion were 110.0 degrees (range, 70 degrees -125 degrees ), 106.1 degrees (range, 70 degrees -120 degrees ), and 111.7 degrees (range, 85 degrees -125 degrees ) for the posterior stabilized, condylar constrained knee, and rotating hinge types, respectively. The rotating hinge group had the highest satisfaction rates (88%). Overall 10-year survivorship was 90.6% with highest survivorship seen in the rotating hinge group. The most common causes for rerevision were infection (2.9% of our cohort), instability (1.7%), and aseptic loosening (1.4%). The mean overall time to rerevision was 69.9 months (range, 11-119 months).
  
  
  CONCLUSIONS
  In our experience periprosthetic infection is the most common cause of failure of both primary and revision TKA. Functional outcome and range of motion improve irrespective of revision implant type. The rotating hinge prosthesis provides patient satisfaction and survivorship similar to that of other implant types.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Department of Trauma and Orthopaedics, University College London Hospital, 250 Euston Road, London NW1 2PG, UK. f.hossain@doctors.org.uk
authors.forename: Fahad
authors.initials: F
authors.lastname: Hossain
authors.forename: Shelain
authors.initials: S
authors.lastname: Patel
authors.forename: Fares Sami
authors.initials: FS
authors.lastname: Haddad
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects* / Q000295:instrumentation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery*; D017060:Patient Satisfaction; D011474:Prosthesis Design; D011475:Prosthesis Failure; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors; D016896:Treatment Outcome