title: Conversion of patellofemoral arthroplasty to total knee arthroplasty: A matched case-control study of 13 patients.
abstract: OBJECTIVE
  The long-term outcome of patellofemoral arthroplasty is related to progression of femorotibial osteoarthritis with need for conversion to total knee arthroplasty. We investigated whether prior patellofemoral arthroplasty compromises the results of total knee arthroplasty.
  
  
  METHODS
  13 patients who had had 14 Richards type II patellofemoral arthroplasties converted to total knee arthroplasty because of femorotibial osteoarthritis, were individually matched to a control group of 13 patients with 14 primary total knee arthroplasties. The mean follow-up times for the patients and the control group were 5.7 (2-13) years and 5.2 (2-13) years, respectively. Clinical outcome was assessed using Knee Society score (KSS), WOMAC score, range of motion, and complications.
  
  
  RESULTS
  KSS and WOMAC scores were similar in the two groups (KSS in patient and control groups: 82 and 86 (p = 0.6); KSS function: 76 and 88 (p = 0.5); WOMAC score: 33 and 21 (p = 0.1)). Within 6 months after conversion, 3 knees had to be manipulated under anesthesia for limited motion. No patients in the control group required manipulation under anesthesia.
  
  
  CONCLUSIONS
  Patellofemoral arthroplasty appears not to have a negative effect on the outcome of later total knee arthroplasty.
authors.affiliation: Department of Orthopedic Surgery, Deventer Hospital, Deventer, the Netherlands. vanjonbergen@dz.nl
authors.forename: Hans-Peter W
authors.initials: HP
authors.lastname: van Jonbergen
authors.forename: Dirk M
authors.initials: DM
authors.lastname: Werkman
authors.forename: Albert
authors.initials: A
authors.lastname: van Kampen
mesh_terms: D000328:Adult; D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods*; D016022:Case-Control Studies; D005260:Female; D005269:Femur / Q000601:surgery; D005500:Follow-Up Studies; D006801:Humans; D007720:Knee Prosthesis / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000601:surgery; D017063:Outcome Assessment, Health Care; D010329:Patella / Q000601:surgery; D011474:Prosthesis Design; D016059:Range of Motion, Articular; D012086:Reoperation; D016896:Treatment Outcome