After stratification on follow-up time and age , the revision rates were not substantially different , aside for younger patients in short term from studies with short-term follow-up .
Conclusion No essential differences between the two design s were observed .
MB and FB UKA design s have comparable revision rates .
Purpose Two design concepts are currently used for unicondylar knee arthroplasty ( UKA ) prostheses :  fixed bearing ( FB ) and mobile bearing ( MB ) .
While MB prostheses have theoretical advantages over their FB counterparts , it is not clear whether they are associated with better outcomes .
Introduction of a new mobile-bearing total knee prosthesis: minimum three year follow-up of an RCT comparing it with a fixed-bearing device.
As part of the step-wise validation of a new prosthesis ( TMK ) , we previously published the 1 year results of a r and omised controlled trial in patients undergoing bilateral knee replacement  [ Price A. , Rees J. , Beard D. , Juszczak E. et al. A mobile-bearing total knee prosthesis compared with a fixed-bearing prosthesis . JBJS B 2003;85-B-1:62 - 7 . ] . Forty patients had the new mobile-bearing prosthesis implanted in one knee and an established fixed-bearing device in the other ( AGC ) . We now report the 3 year status of these patients and , in addition , review a separate multi-centre cohort of 172 patients who had undergone unilateral arthroplasty with the TMK .  No significant differences were found in outcome ( American Knee Society Score and Oxford Knee Score ) between the two prostheses . The greater incidence of " clicking " in the mobile-bearing knee , reported in the previous review , persisted ( TMK=48 % , AGC=30 % ) . The presence of this mechanical noise was found to have no relationship with outcome in either of the prostheses . The unilateral cohort study showed an acceptable complication rate for the new prosthesis , although some patients reported subjective instability . The method of controlled introduction of the TMK , of which this constitutes a further step , has allowed us to assess the significance of a reported problem ( clicking ) and to provide scientific data from which other surgeons can decide about use of the implant
After stratification on follow-up time and age , the revision rates were not substantially different , aside for younger patients in short term from studies with short-term follow-up .
Conclusion No essential differences between the two design s were observed .
MB and FB UKA design s have comparable revision rates .
Purpose Two design concepts are currently used for unicondylar knee arthroplasty ( UKA ) prostheses :  fixed bearing ( FB ) and mobile bearing ( MB ) .
While MB prostheses have theoretical advantages over their FB counterparts , it is not clear whether they are associated with better outcomes .