title: Similar TKA designs with differences in clinical outcome: a randomized, controlled trial of 77 knees with a mean follow-up of 6 years.
abstract: OBJECTIVE
  To try to improve the outcome of our TKAs, we started to use the CKS prosthesis. However, in a retrospective analysis this design tended to give worse results. We therefore conducted a randomized, controlled trial comparing this CKS prosthesis and our standard PFC prosthesis. Because many randomized studies between different TKA concepts generally fail to show superiority of a particular design, we hypothesized that these seemingly similar designs would not lead to any difference in clinical outcome.
  
  
  METHODS
  82 patients (90 knees) were randomly allocated to one or other prosthesis, and 39 CKS prostheses and 38 PFC prostheses could be followed for mean 5.6 years. No patients were lost to follow-up. At each follow-up, patients were evaluated clinically and radiographically, and the KSS, WOMAC, VAS patient satisfaction scores and VAS for pain were recorded.
  
  
  RESULTS
  With total Knee Society score (KSS) as primary endpoint, there was a difference in favor of the PFC group at final follow-up (p = 0.04). Whereas there was one revision in the PFC group, there were 6 revisions in the CKS group (p = 0.1). The survival analysis with any reoperation as endpoint showed better survival in the PFC group (97% (95% CI: 92-100) for the PFC group vs. 79% (95% CI: 66-92) for the CKS group) (p = 0.02).
  
  
  CONCLUSIONS
  Our hypothesis that there would be no difference in clinical outcome was rejected in this study. The PFC system showed excellent results that were comparable to those in previous reports. The CKS design had differences that had considerable negative consequences clinically. The relatively poor results have discouraged us from using this design.
authors: Department of Orthopaedics, Radboud University, Nijmegen Medical Centre, the Netherlands. hjmeijerink@hotmail.com
authors: Huub J
authors: HJ
authors: Meijerink
authors: Nico
authors: N
authors: Verdonschot
authors: Corné J M
authors: CJ
authors: van Loon
authors: Gerjon
authors: G
authors: Hannink
authors: Maarten C
authors: MC
authors: de Waalmalefijt
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging; D007720:Knee Prosthesis / Q000009:adverse effects; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011859:Radiography; D016059:Range of Motion, Articular; D012086:Reoperation; D016896:Treatment Outcome