Similarly , no difference was revealed between the groups for radiological outcomes or general health results .
Controversy exists regarding the clinical and radiological differences in outcomes between  fixed-bearing ( FB ) and mobile-bearing ( MB ) total knee arthroplasties ( TKAs ) at the mid- or long-term follow-up .
We therefore conducted a meta- analysis and systematic review of r and omized controlled trials ( RCTs ) that have evaluated FB and MB TKAs .
Mobile-bearing insert translational and rotational kinematics in a PCL-retaining total knee arthroplasty.
INTRODUCTION  Total knee prostheses  with a mobile-bearing insert were developed to provide nonconstrained joint range of motion while reducing friction forces . The purpose of this study was , based on weightbearing X-rays , to evaluate the mobility of the polyethylene tibial insert in relation to the femoral and tibial components . We studied the results of a cementless total knee arthroplasty ( TKA ) retaining the posterior cruciate ligament ( PCL ) , with a mobile-bearing platform in rotation and anteroposterior translation ( Innex Anterior-Posterior Glide , Zimmer ) with a mean 23-month follow-up duration after surgery . HYPOTHESIS Both anterior-posterior tibiofemoral translation and intraprosthetic axial rotation occur between the mobile polyethylene insert and the tibial endplate . MATERIAL AND METHOD In a series of 51 primary TKA , the three-dimensional ( 3D ) kinematics of the femoral , tibial , and mobile insert components were determined using a computerized matching system between the prosthetic 3D models and the radiographic images of the implants on three lateral follow-up weightbearing knee X-rays : films were taken in full extension , at 45 degrees flexion , and at maximum flexion . RESULTS There was a statistically significant increase in the internal rotation of the mobile tray with flexion , ( up to a mean -3+/-3 degrees between the femoral box and the mobile tray [ p<0.0001 ] and up to a mean -5+/-7 degrees between the tibial tray and the mobile tray [ p<0.0001 ] ) . The mobile tray did not translate in relation to the tibial endplate from extension to 45 degrees flexion ( 0+/-2 mm [ range : -5 to 6 mm ] ) . However , from 45 degrees to maximum flexion , a statistically significant mean 1+/-2 mm ( range : -2 to 9 mm ) of anterior translation ( p<0.0001 ) was found . DISCUSSION The extent of insert mobility varies from one study to another . Some have reported relatively limited mobility stemming from a superior surface that is not highly congruent , ( thus allowing anterior-posterior and mediolateral translation through gliding of the femur in contact with the insert ) . Other studies have reported mobile-bearing tray mobility in relation to the tibial endplate and minimal rotation at the femoral component level . In this series of PCL retaining TKA with a mobile-bearing platform , the mobile-bearing platform showed a progressive increase in internal rotation during flexion . Most of this rotational mobility occurred between the mobile platform and the tibial endplate , confirming our hypothesis . However , with flexion , the femoral component increased its mobility relatively to the platform . During flexion , an anterior-posterior translation occurred between the femoral implant and the tibial insert , and between the tibial insert and the tibial endplate , but the direction of the mobile tibial insert translation remained unpredictable with this nonconstrained implant design used . LEVEL OF EVIDENCE Level IV . Prospect i ve non-controlled therapeutic study
Similarly , no difference was revealed between the groups for radiological outcomes or general health results .
Controversy exists regarding the clinical and radiological differences in outcomes between  fixed-bearing ( FB ) and mobile-bearing ( MB ) total knee arthroplasties ( TKAs ) at the mid- or long-term follow-up .
We therefore conducted a meta- analysis and systematic review of r and omized controlled trials ( RCTs ) that have evaluated FB and MB TKAs .