title: How do knee implants perform past the second decade? Nineteen- to 25-year followup of the Press-fit Condylar design TKA.
abstract: BACKGROUND
  At 14- to 17-year followup, we reported successful outcomes of the Press-fit Condylar total knee arthroplasty (TKA) system in 160 TKAs performed between 1986 and 1989. However, there are few published reports on TKA survivorship and patient function that include patients evaluated into the third decade after surgery.
  
  
  OBJECTIVE
  The study purpose was to determine (1) the survivorship of the implant; and (2) knee function in patients with this TKA system at a mean 20-year followup.
  
  
  METHODS
  We ascertained revision status of all living patients (42 of 160 knees) and all patients (22 knees) who died since the previous study. Among patients alive at the latest followup, Knee Society function scores were obtained and radiographs were evaluated. Kaplan-Meier survivorship analysis with 95% confidence intervals was performed with revision for any reason and aseptic loosening as endpoints. A competing risks analysis with 95% confidence intervals was also performed for revision for any reason as the endpoint.
  
  
  RESULTS
  At the mean 20-year (range, 19-25 years) followup, all living patients retained their original implants from the index TKA, exclusive of three polyethylene exchanges. This study demonstrates an 87% Kaplan-Meier survivorship for revision for any reason (95% confidence interval [CI], 80%-92%) and a 98% Kaplan-Meier survivorship for revision for aseptic loosening (95% CI, 93%-99%). Competing risks survivorship was 79% (95% CI, 70%-85%) at 25 years for revision for any reason. Mean Knee Society function score was 46.9. Since the previous study, three revisions have been performed, all for polyethylene wear.
  
  
  CONCLUSIONS
  The Press-fit Condylar implant system continues to be successful, maintaining longevity up to 25-year followup. This is one of the longest followup studies, reporting continued successes over 20 years, and should serve as a benchmark for current-generation implants.
  
  
  METHODS
  Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
authors.affiliation: Shiley Center for Orthopaedic Research & Education, 11025 North Torrey Pines Road, Suite 200, La Jolla, CA, 92037, USA.
authors.forename: Shantanu
authors.initials: S
authors.lastname: Patil
authors.forename: Julie C
authors.initials: JC
authors.lastname: McCauley
authors.forename: Pamela
authors.initials: P
authors.lastname: Pulido
authors.forename: Clifford W
authors.initials: CW
authors.lastname: Colwell
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000295:instrumentation*; D001696:Biomechanical Phenomena; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D053208:Kaplan-Meier Estimate; D007719:Knee Joint / Q000000981:diagnostic imaging / Q000503:physiopathology / Q000601:surgery*; D007720:Knee Prosthesis; D008297:Male; D008875:Middle Aged; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D020127:Recovery of Function; D012086:Reoperation; D012307:Risk Factors; D013314:Stress, Mechanical; D013997:Time Factors; D016896:Treatment Outcome
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