Higher forgotten joint score for fixed-bearing than for mobile-bearing total knee arthroplasty

Knee Surg Sports Traumatol Arthrosc. 2016 Aug;24(8):2641-5. doi: 10.1007/s00167-015-3663-z. Epub 2015 Jun 3.


Purpose: To compare the postoperative subjective outcome for fixed- and mobile-bearing total knee arthroplasty (TKA) by using the forgotten joint score (FJS-12), a new patient-reported outcome score of 12 questions evaluating the potential of a patient to forget about his operated joint. The hypothesis of this study was that a mobile-bearing TKA would have a higher level of forgotten joint than a fixed-bearing model of the same design.

Methods: A retrospective cohort study was conducted in 100 patients who underwent TKA at least 1 year [mean (SD) 18 (5) months] before with either a fixed-bearing (N = 50) or a mobile-bearing (N = 50) TKA from the same implant family. Clinical outcome was evaluated with the knee society score and patient-reported outcome with the forgotten joint score.

Results: No difference was observed for demographics in between both study groups. The mean (SD) postoperative FJS-12 for the fixed-bearing TKA was 71 (28) compared to a mean (SD) of 56.5 (30) for the mobile-bearing TKA.

Discussion: The clinical relevance of the present retrospective study is that it shows for the first time a significant difference between fixed- and mobile-bearing TKA by using a new patient-reported outcome score. The hypothesis that mobile-bearing TKA would have a higher degree of forgotten joint than a fixed-bearing TKA could not be confirmed. A level I prospective study should be set up to objectivise these findings.

Level of evidence: IV.

Keywords: Fixed bearing; Forgotten joint score; Mobile bearing; Total knee arthroplasty.

MeSH terms

  • Aged
  • Arthroplasty, Replacement, Knee / instrumentation*
  • Female
  • Humans
  • Knee Joint / physiology
  • Knee Joint / surgery
  • Knee Prosthesis*
  • Male
  • Middle Aged
  • Osteoarthritis, Knee / physiopathology
  • Osteoarthritis, Knee / surgery
  • Patient Reported Outcome Measures*
  • Postoperative Period
  • Prosthesis Design
  • Range of Motion, Articular
  • Retrospective Studies