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 .
Comparison of the tibiofemoral rotational alignment after mobile and fixed bearing total knee arthroplasty
Purpose The anatomical l and mark for the anteroposterior ( AP ) axis of the proximal tibia and its variability was investigated in order to determine whether a certain l and mark could be employed as a reference axis for the proximal tibia after the rotating platform mobile bearing and fixed bearing total knee arthroplasties ( TKAs ) . Methods Eighty primary osteoarthritic knees were r and omized to undergo either rotating platform mobile bearing ( Group A , n = 40 ) or fixed bearing ( Group B , n = 40 ) TKAs , and were followed up for 31 and 30 months , respectively . The AP axes were defined for the distal femur , proximal tibia , ankle , and each TKA component on the reconstructed CT scan and the angles between the distal femoral AP axis and those of each bone or component were estimated . Clinical and radiographic outcomes were evaluated during the follow up . Results A significant difference was seen between the preoperative and postoperative rotational position of the proximal tibia relative to the distal femur following rotating platform mobile bearing TKA ( P = 0.014 ) whereas no such difference was seen after fixed bearing TKA .  The mean postoperative alignment of the tibia differed between the two groups ( Group A : Group B = −2.9:0.2 , P = 0.010 ) and its variability was significantly greater in group A ( P < 0.001 ) . There were no differences in the clinical outcomes including range of motion , knee society score , function score , HSS , and WOMAC score as well as the mean postoperative coronal tibiofemoral alignment between the two groups . Conclusion The unpredictable change in the rotational axis of the tibia and its broad variability after rotating platform mobile bearing TKA may provide a warning against the use of a fixed l and mark for establishing tibial rotational alignment . Level of evidence Prospect i ve comparative study , Level II
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 .