Meta-analyses showed no clinical ly relevant differences in terms of revision rates , clinical outcome scores or patient-reported outcome measures between MB and FB TKRs .
It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice
Mobile-bearing ( MB ) total knee replacement ( TKR ) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts .
However , no consistent clinical advantages of mobile- over fixed-bearing ( FB ) TKR have been found .
In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores .
Furthermore , we determined which modifying variables affected the outcome .
The Knee Arthroplasty Trial (KAT) design features, baseline characteristics, and two-year functional outcomes after alternative approaches to knee replacement.
BACKGROUND The aim of continued development of total knee replacement systems has been the further improvement of the quality of life and increasing the duration of prosthetic survival . Our goal was to evaluate the effects of several design features , including metal backing of the tibial component , patellar resurfacing , and a mobile bearing between the tibial and femoral components , on the function and survival of the implant . METHODS A pragmatic , multicenter , r and omized , controlled trial involving 116 surgeons in thirty-four centers in the United Kingdom was performed ; 2352 participants were r and omly allocated to be treated  with or without a metal backing of the tibial component ( 409 ) , with or without patellar resurfacing ( 1715 ) , and /or with or without a mobile bearing ( 539 ) . R and omization to more than one comparison was allowed . The primary outcome measures were the Oxford Knee Score ( OKS ) , Short Form-12 , EuroQol-5D , and the need for additional surgery . The results up to two years postoperatively are reported . RESULTS Functional status and quality -of-life scores were low at baseline but improved markedly across all trial groups following knee replacement ( mean overall OKS , 17.98 points at baseline and 34.82 points at two years ) . Most of the change was observed at three months after the surgery . Six percent of the patients had additional knee surgery within two years . There was no evidence of differences in clinical , functional , or quality -of-life measures between the r and omized groups at two years . CONCLUSIONS Patients have substantial improvement following total knee replacement . This is the first adequately powered r and omized controlled trial , of which we are aware , in which the effects of metal backing , patellar resurfacing , and a mobile bearing were investigated . We found no evidence of an effect of these variants on the rate of early complications or on functional recovery up to two years after total knee replacement
Meta-analyses showed no clinical ly relevant differences in terms of revision rates , clinical outcome scores or patient-reported outcome measures between MB and FB TKRs .
It appears that theoretical assumptions of superiority of MB over FB TKR are not borne out in clinical practice
Mobile-bearing ( MB ) total knee replacement ( TKR ) was introduced to reduce the risk of aseptic loosening and wear of polyethylene inserts .
However , no consistent clinical advantages of mobile- over fixed-bearing ( FB ) TKR have been found .
In this study we evaluated whether mobile bearings have an advantage over fixed bearings with regard to revision rates and clinical outcome scores .
Furthermore , we determined which modifying variables affected the outcome .