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 .
Mobile and fixed-bearing (all-polyethylene tibial component) total knee arthroplasty designs. A prospective randomized trial.
BACKGROUND Proponents of mobile-bearing total knee arthroplasty believe that it has potential advantages over a fixed-bearing design in terms of diminished wear and improved motion and /or function , but these advantages have not been demonstrated in a r and omized clinical comparison to our knowledge . We conducted a patient-blinded , prospect i ve , r and omized clinical trial to compare mobile-bearing and fixed-bearing cruciate-substituting total knee arthroplasties of the same design . METHODS Patients between the ages of sixty and eighty-five years were prospect ively r and omized to receive a cruciate-substituting rotating-platform design or a fixed-bearing design with an all-polyethylene tibial component . There were no significant differences in the demographic characteristics ( mean age , 72.2 years ; mean American Society of Anesthesiologists score , 2.7 ; mean body mass index , 31.8 kg/m(2 ) ) or preoperative clinical or radiographic measures between the groups . Routine clinical and radiographic follow-up measures included the Knee Society score ( KSS ) , Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) , and Short Form-36 ( SF-36 ) outcome measures . RESULTS The results of 312 arthroplasties ( 136 with an all-polyethylene tibial component  and 176 rotating-platform design s ) in 273 patients were analyzed at a minimum of two years ( mean , forty-two months ) postoperatively . Although there was significant improvement in both groups , there was no significant difference between the groups with regard to the mean postoperative range of motion ( 110.9 degrees and 109.1 degrees , respectively ; p = 0.21 ) , the mean KSS clinical score ( 90.4 and 88.2 points ; p = 0.168 ) , or the mean KSS pain score ( 44.9 and 43.1 points ; p = 0.108 ) at this follow-up point . There were ten revisions : seven because of infection , one because of patellar fracture , one because of instability , and one because of aseptic loosening . CONCLUSIONS The two design s functioned equivalently at the time of early follow-up in this low-to-moderate-dem and patient group . The rotating-platform design had no significant clinical advantage over the design with the all-polyethylene tibial component
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 .