Differences in long-term fixation between mobile-bearing and fixed-bearing knee prostheses at ten to 12 years' follow-up: a single-blinded randomised controlled radiostereometric trial. Mobile vs. fixed meniscal bearing in total knee replacement: a randomised radiostereometric study. A prospective randomised study comparing rotating platform and fixed bearing total knee arthroplasty in a cruciate substituting design--outcomes at two year follow-up. Gait analysis of fixed bearing and mobile bearing total knee prostheses during walking: do mobile bearings offer functional advantages? Mobile and fixed-bearing (all-polyethylene tibial component) total knee arthroplasty designs. A prospective randomized trial. Kinematics and early migration in single-radius mobile- and fixed-bearing total knee prostheses. A randomised controlled clinical trial and gait analysis of fixed- and mobile-bearing total knee replacements with a five-year follow-up. Mobile Bearings Do Not Improve Fixation in Cemented Total Knee Arthroplasty The John Insall Award: No Functional Advantage of a Mobile Bearing Posterior Stabilized TKA Mobile-bearing insert translational and rotational kinematics in a PCL-retaining total knee arthroplasty. [Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomized clinical and radiological study]. Fixed-bearing versus mobile-bearing total knee arthroplasty: a prospective randomised, clinical and radiological study with mid-term results at 7 years. Comparison of Fixed-Bearing and Mobile-Bearing Total Knee Arthroplasties Staged bilateral mobile-bearing and fixed-bearing total knee arthroplasty in the same patients: a prospective comparison of a posterior-stabilized prosthesis Long-term comparison of fixed-bearing and mobile-bearing total knee replacements in patients younger than fifty-one years of age with osteoarthritis. Fixed versus mobile weight-bearing prosthesis in total knee arthroplasty Mobile-bearing prosthesis did not improve mid-term clinical results of total knee arthroplasty
This single-blinded r and omised controlled trial investigated whether one design of mobile-bearing ( MB ) total knee replacement ( TKR ) has any advantage over a fixed-bearing ( FB ) design on long-term fixation as measured by radiostereometry . The amount of wear underneath the mobile bearing was also evaluated . A series of 42 knees was r and omised to MB or FB tibial components with appropriate polyethylene inserts and followed for between ten and 12 years , or until the death of the patient . The polyethylene in the MB group was superior in that it was gamma-irradiated in inert gas and was calcium-stearate free ; the polyethylene in the FB group was gamma-irradiated in air and contained calcium stearate . In theory this should be advantageous to the wear rate of the MB group . At final follow-up the overall mean migration was 0.75 mm ( SD 0.76 ) in the MB group and 0.66 mm ( SD 0.4 ) in the FB group , with the FB group demonstrating more posterior tilt and the MB group more internal rotation . In the FB group there was one revision for aseptic loosening , but none in the MB group . There were no significant differences in clinical or radiological scores . For the MB group , the mean linear wear rate on the under-surface was 0.026 mm/year ( SD 0.014 ) . This was significantly smaller than the wear rate of 0.11 mm/year ( SD 0.06 ) in the MB between femur and polyethylene ( p < 0.001 ) . Nevertheless , even in a best-case setting the mobile bearings of this TKR design had no apparent advantage in terms of fixation over the FB knee prosthesis at ten to 12 years . The wear underneath the mobile bearing was small and is unlikely to be clinical ly relevant 52 knees scheduled for a total knee arthroplasty were r and omised to either a fixed or a mobile polyethylene bearing . The design was identical in all parts . The knee systems used were the Rotaglide Total Knee System ( RTK ) and the Nuffield Total Knee System ( NTK ) , both from the same manufacturer ( Corin Medical Ltd. , UK ) . All knees implanted were uncemented . The patients were followed for 2 years clinical ly and with radiostereometric analyses to assess migration over time and inducible displacement of the tibial component . Separate analysis of the mobility of the tibial insert in the knees with a mobile bearing was also made . The migration measured with RSA between the 1st and 2nd year expressed as maximum total point motion ( MTPM ) might predict the risk of loosening of the implant . There were no differences between the groups regarding clinical outcome ( HSS Knee score ) , migration or inducible displacement during the 2 years follow-up . The movement between the tibial tray and the mobile meniscal insert expressed as maximum total point motion ( MTPM ) was 6.8+/-3.3 mm at the 1st year follow-up BACKGROUND Fixed bearing ( FB ) total knee replacement is a well established technique against which new techniques must be compared . Mobile bearing ( MB ) prostheses , in theory , reduce polyethylene wear but the literature is yet to provide evidence that they are superior in terms of function or long-term survivorship . In addition there has been no comparison of patella resurfacing on the outcome of either design . The aims of this r and omised prospect i ve study were firstly to determine whether a mobile bearing prosthesis produced better clinical outcome and range of motion at two year follow-up and secondly to assess the effect of patella resurfacing on the outcomes of both types of bearing design . METHODS Three hundred fifty-two patients were r and omised into receiving either a PFC Sigma © cruciate sacrificing total knee arthroplasty either with a mobile bearing or a fixed bearing  , with a sub-r and omisation to either patella resurfacing or patella retention . All patients participated with st and ard clinical outcome measures and had their range of motion measured both pre-operatively and at follow-up . RESULTS The mobile bearing TKR design had no impact on range of motion ; Oxford Knee Score and American Knee Society knee and function scores when compared to its fixed bearing equivalent . CONCLUSIONS At two year follow-up there was no difference between the PFC Sigma © fixed and mobile bearing design s. With no clinical difference between the cohorts , we can not recommend one design over the other . Long term benefits , particularly with regards to polyethylene wear , may yet be demonstrated . Level of evidence --1B BACKGROUND Limited previous findings have detailed biomechanical advantages following implantation with mobile bearing ( MB ) prostheses after total knee replacement ( TKR ) surgery during walking . The aim of this study was to compare three dimensional spatiotemporal , kinematic , and kinetic parameters during walking to examine whether MBs offer functional advantages over fixed bearing ( FB ) design s. METHODS Sixteen patients undergoing primary unilateral TKR surgery were r and omised to receive either a FB ( n=8 ) or MB ( n=8 ) total knee prosthesis .  Eight age and gender matched controls underwent the same protocol on one occasion . A 12 camera Vicon system integrated with four force plates was used . Patients were tested pre-surgery and nine months post-surgery . RESULTS No significant differences between FB and MB groups were found at any time point in the spatiotemporal parameters . The MB group was found to have a significantly reduced frontal plane knee range of motion ( ROM ) at pre-surgery than the FB group ( FB=14.92±4.02 ° ; MB=8.87±4.82 ° ) , with the difference not observed post-surgery . No further significant kinematic or kinetic differences were observed between FB and MB groups . Fixed bearing and MB groups both displayed spatiotemporal , kinematic , and kinetic differences when compared to controls . Fixed bearing and MB groups differed from controls in six and five parameters at nine months post-surgery , respectively . CONCLUSIONS No functional advantages were found in knees implanted with MB prostheses during walking , with both groups indicative of similar differences when compared to normal knee biomechanics following prosthesis implantation . LEVEL OF EVIDENCE Level II 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 BACKGROUND The mobile-bearing variant of a single-radius design is assumed to provide more freedom of motion compared to the fixed-bearing variant because the insert does not restrict the natural movements of the femoral component . This would reduce the contact stresses and wear which in turn may have a positive effect on the fixation of the prosthesis to the bone and thereby decreases the risk for loosening . The aim of this study was to evaluate early migration of the tibial component and kinematics of a mobile-bearing and fixed-bearing total knee prosthesis of the same single-radius design . METHODS Twenty Triathlon single-radius posterior-stabilized knee prostheses were implanted ( 9 mobile-bearing and 11 fixed-bearing ) .  Fluoroscopy and roentgen stereophotogrammetric analysis ( RSA ) were performed 6 and 12 months post-operatively . FINDINGS The 1 year post-operative RSA results showed considerable early migrations in 3 out of 9 mobile-bearing patients and 1 out of 11 fixed-bearing patients . The range of knee flexion was the same for the mobile-bearing and fixed-bearing group . The mobile insert was following the femoral component during motion . INTERPRETATION Despite the mobile insert following the femoral component during motion , and therefore performing as intended , no kinematic advantages of the mobile-bearing total knee prosthesis were seen . The fixed-bearing knee performed as good as the mobile-bearing knee and maybe even slightly better based on less irregular kinematics and less early migrations This study compared the outcome of  total knee replacement ( TKR ) in adult patients with fixed- and mobile-bearing prostheses during the first post-operative year and at five years ' follow-up , using gait parameters as a new objective measure . This double-blind r and omised controlled clinical trial included 55 patients with mobile-bearing ( n = 26 ) and fixed-bearing ( n = 29 ) prostheses of the same design , evaluated pre-operatively and post-operatively at six weeks , three months , six months , one year and five years . Each participant undertook two walking trials of 30 m and completed the EuroQol question naire , Western Ontario and McMaster Universities osteoarthritis index , Knee Society score , and visual analogue scales for pain and stiffness . Gait analysis was performed using five miniature angular rate sensors mounted on the trunk ( sacrum ) , each thigh and calf . The study population was divided into two groups according to age ( ≤ 70 years versus > 70 years ) .  Improvements in most gait parameters at five years ' follow-up were greater for fixed-bearing TKRs in older patients ( > 70 years ) , and greater for mobile-bearing TKRs in younger patients ( ≤ 70 years ) . These findings should be confirmed by an extended age controlled study , as the ideal choice of prosthesis might depend on the age of the patient at the time of surgery Mobile bearings were introduced to improve wear and knee kinematics . By uncoupling the forces generated at the articulation from the implant-bone interface this would , theoretically , also improve the fixation of the implant to bone . We did this study to evaluate whether mobile bearings  improve the fixation of the tibial component to bone .  Fifty-two consecutive knees in 47 patients ( average age , 72 years ; range , 62 - 84 years ) with primary osteoarthrosis were r and omized into two groups to receive a cemented total knee arthroplasty with either a fixed-bearing or mobile-bearing tibial component . The quality of fixation was analyzed with radiostereometric analysis for up to 2 years . Mobile bearings did not improve fixation . Both magnitudes and directions of component rotations were similar , and the number of implants with continuous migration was almost identical . Both implant types had a combination of subsidence and lift-off , but where the mobile bearing implants displayed more of subsidence , the fixed bearing knees showed more lift-off . It might be that the somewhat stiffer cobalt-chromium baseplate or the different joint conformity used in the mobile-bearing knees counteracts any potential effects of the mobile bearing . Level of Evidence : Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence Background Mobile bearing ( MB ) total knee design has been advocated as a means to enhance the functional characteristics and decrease the wear rates of condylar total knee arthroplasty ( TKA ) . However , it is unclear if these design s achieve these goals . Questions / purpose sWe asked whether function of patients or survivorship would be greater or complications would be lesser in groups of patients with MB compared with fixed bearing ( FB ) TKA .  We also sought to describe retrieval findings . Methods We r and omized 507 primary TKAs in 416 eligible patients to receive MB ( n = 252 ) or FB ( n = 255 ) devices from November 2001 to August 2007 ( Investigational Device Exemption G000180 , Clinical Trials.gov registration number NCT00946075 ) . Patients were blinded to treatment allocation . WOMAC Index , SF-12 Health Survey , knee range of motion , and Knee Society scores were collected and compared preoperatively and at 6 , 12 , and 24 months postoperatively . We recorded device failures and complications until October 2009 . Kaplan-Meier survivorship was compared using the log rank test . Twelve retrieved MB devices underwent pathologic analysis . The minimum postoperative time was 2.2 years ( mean , 5.9 years ; range , 2.2–7.9 years ) . Results We found no differences in mean clinical assessment scores or mean score changes from baseline at any postoperative interval through 2 postoperative years . Nineteen of the 252 MB and 13 of the 255 FB knees had undergone revision of any component . Estimated survival at 6 postoperative years was similar for the two devices : 90.1 % ( 95 % confidence interval [ CI ] , 84.1–93.9 ) for MB and 94.2 % ( 95 % CI , 90.1–96.6 ) for FB . Two MB and no FB tibial components were revised for loosening . There was one case of MB insert dislocation . Retrieved MB devices demonstrated no unexpected wear or mechanical device failures . Conclusion We found no evidence of functional advantage of the MB design . Survivorship was similar , although the study is limited by short duration of followup . Level of Evidence Level I , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence 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 PURPOSE OF THE STUDY Mobile-bearing total knee arthroplasty has become increasingly popular over the last few years since this option presents several theoretical advantages compared with the fixed-bearing models . The clinical advantage remains to be demonstrated . We therefore conducted a prospect i ve r and omized trial to ascertain the potential benefits . MATERIAL AND METHODS This study included patients treated by three senior orthopedic surgeons . Each group included 52 prostheses in 52 patients in the fixed-bearing group and 50 patients in the mobile-bearing group . The per- and postoperative protocol s were the same for both groups . Implants were cemented in all cases and patellae were resurfaced . The SF-12 , the Knee Society Score ( KSS ) , the Hospital of Special Surgery score ( HSS ) and pain and joint motion were noted before and after surgery . RESULTS Among the 104 prostheses implanted , 100 were review ed at mean follow-up of 36 months ( range 24 - 41 ) . One patient in the fixed-bearing group died six months after surgery from an unrelated cause . Three patients were lost to follow-up : one in the fixed-bearing group and two in the mobile-bearing group . There was no difference between groups for the SF-12 , KSS , HSS , pain and joint motion measured postoperatively . Postoperative femorotibial alignment was one degree varus on average in the fixed-bearing group and zero degree in the mobile-bearing group . At last follow-up , there were no radiological signs of prosthesis loosening . One patient in the fixed-bearing group developed a deep venous thrombosis , complicated by pulmonary embolism . Two of the mobile-bearing prostheses were revised , one for patellar fracture caused by a bicycle accident and one for prosthesis infection in a patient with endocarditis 1.5 years after implantation . DISCUSSION The clinical results were similar for the two groups in terms of function , pain , general status and complications . The outcome at 36 months was considered excellent or good in 90 % of the fixed-bearing group and 88 % in the mobile-bearing group . This study did not reveal any difference between the two groups regarding maximal flexion and anterior knee pain , two parameters which would theoretically show short-term improvement with the mobile bearing . Mid- and long-term follow will be required to confirm these findings and to determine the survival of these two types of implants Mobile-bearing ( MB ) total knee arthroplasty ( TKA ) was developed as an alternative to the established fixed-bearing ( FB ) design because of theoretical advantages . Short-term studies comparing these design s have not shown any differences in clinical and radiographic results . We compared the results at 7 years of a r and omised study of patients undergoing TKA using either a FB or a MB variant of the same prosthesis . Fifty-two patients ( 52 knees ) with an average age of 70 years received a FB posterior-stabilized prosthesis , and 50 patients ( 52 knees ) with an average age of 72 years , a MB prosthesis .  All implants were cemented and the patella was routinely resurfaced . Preoperatively , there were no differences between the two groups , and surgical procedure and postoperative protocol were the same for both . At an average follow-up of 7.1 years , no significant differences of FB over MB design could be demonstrated with respect to the American Knee Society score ( AKSS ) , pain score , a question naire of general health ( SF-12 score ) , range of motion ( ROM ) , or complication rates . Radiographs showed no significant difference in prosthetic alignment or evidence of loosening . Two knees with a MB design required reoperation , one for persistent joint stiffness and another to treat septic loosening . One patient with a MB prosthesis with signs of tibial component loosening was asymptomatic . We conclude that at mid-term follow-up there is no evidence to prove the superiority of MB over FB TKA with regard to the clinical and radiographic results The purpose of the current study was to directly compare the results of fixed-bearing and mobile-bearing total knee arthroplasties in the same patient who had bilateral simultaneous total knee replacements . A fixed-bearing total knee prosthesis ( AMK ) was implanted in one knee and a mobile-bearing total knee prosthesis ( LCS ) was implanted in the other knee in 116 patients . The average age of the patients was 65 years ( range , 33–70 years ) . The average followup was 7.4 years ( range , 6–8 years ) .  Clinical and radiographic followup was done using Knee Society and Hospital for Special Surgery knee rating systems at 6 weeks , 3 months , 6 months , 1 year after surgery , and yearly thereafter . Total knee score , pain score , mean functional score , and range of motion were comparable in both groups . Two knee replacements ( 2 % ) in one patient with AMK prostheses were revised because of complete wear of tibial bearing polyethylene . One knee replacement ( 1 % ) in one patient with an LCS prosthesis was revised because of dislocation of the medial tibial bearing polyethylene and one knee replacement ( 1 % ) in one patient with an LCS prosthesis was revised because of complete wear of the medial tibial bearing polyethylene . No knee had aseptic loosening or osteolysis in either group . After a minimum followup of 6 years , the results of fixed- and mobile-bearing total knee prostheses in the current series are favorable . However , there is no evidence to prove the superiority of the mobile-bearing total knee design Mobile-bearing total knee arthroplasty ( TKA ) has several theoretical advantages over fixed-bearing TKA . We conducted a prospect i ve r and omized trial to compare the results of mobile-bearing and fixed-bearing posterior-stabilized TKA in the same patients using the same femoral component design of a mobile-bearing prosthesis in one knee and a fixed-bearing prosthesis in the other knee in 25 patients with osteoarthritis . The mean follow-up was 40 months . No significant differences were found in the mobile-bearing and fixed-bearing knees in terms of clinical and radiographic results . No osteolysis , loosening , or revision occurred . One knee with a mobile-bearing prosthesis had a dislocation of the rotating bearing ; however , spontaneous reduction occurred and the dislocation did not recur . Satisfactory early results can be achieved in both mobile-bearing and fixed-bearing knees . We could not demonstrate an advantage of a mobile-bearing TKA BACKGROUND There is limited information comparing the results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in patients with osteoarthritis who are younger than fifty-one years and who have a fixed-bearing implant in one knee and a mobile-bearing implant  in the other . The purpose of this study was to compare our long-term clinical and radiographic results of fixed-bearing total knee replacement and mobile-bearing total knee replacement in a group of patients from this population . METHODS We prospect ively compared the results of 108 patients with osteoarthritis who were younger than fifty-one years ( mean age , forty-five years ) who had received a fixed-bearing prosthesis in one knee and a rotating platform mobile-bearing prosthesis in the other .  The mean follow-up was 16.8 years ( range , fifteen to eighteen years ) . The patients were assessed clinical ly and radiographically . Knee motion and function were assessed as a primary outcome . Patients were assessed with question naires , and each knee was assessed separately . RESULTS Although there was significant improvement in both groups of knees , there was no significant difference between the groups ( i.e. , fixed-bearing and mobile-bearing knees ) with regard to the mean postoperative knee motion ( 126 ° and 128 ° , respectively ; p = 0.79 ) , the mean Knee Society knee clinical score ( 95 and 94 points , respectively ; p = 0.79 ) , or the Knee Society knee functional score ( 84 and 85 points , respectively ; p = 0.19 ) at the latest follow-up . In the fixed-bearing group , one knee was revised because of infection , two for aseptic loosening of the tibial component , and two because of wear of the tibial polyethylene insert . In the rotating platform mobile-bearing group , two knees were revised because of instability and one because of infection . The Kaplan-Meier survivorship for revision at 16.8 years of follow-up was 95 % ( 95 % confidence interval , 91 to 100 ) for the fixed-bearing prosthesis and 97 % ( 95 % confidence interval , 93 to 100 ) for the rotating platform mobile-bearing prosthesis . CONCLUSIONS Long-term results of both fixed and mobile-bearing total knee arthroplasties were encouraging in patients who were younger than fifty-one years of age with osteoarthritis . However , we found no superiority of the mobile-bearing total knee prosthesis over the fixed-bearing total knee prosthesis Purpose This study was design ed to compare clinical , radiological , and general health results of two prostheses ( mobile vs. fixed weight-bearing devices ) that are used in total knee arthroplasty with a 5-year follow-up . Methods This r and omized controlled study was conducted from 2004 to 2010 in the Department of Orthopedic Surgery at two university hospitals in Isfahan , Iran . Three hundred patients with expected primary total knee arthroplasty ( TKA ) without severe deformity ( a fixed varus or valgus deformity greater than 20 ° ) received fixed weight-bearing ( n = 150 ) or mobile weight-bearing ( n = 150 ) devices . Clinical , radiological , and quality of life outcomes were compared between the two groups at six-month intervals for the first year , after which the comparisons were made annually for the next 4 years . Results Both groups had similar baseline characteristics . Although there was significant improvement in both groups , there was no significant difference between the groups with regard to the means of the Knee Society Scores , which were 92 ( SD : 12.1 ) for the fixed weight-bearing device and 93 ( SD : 14.2 ) for the mobile weight-bearing device ( n.s . ) at the final follow-up point . Radiographs showed that there was no significant difference in prosthetic alignment and no evidence of loosening . After TKA , the SF-36 score increased in both groups , but there was no statistical difference between the groups in quality of life at the final follow-up ( 62 ( 12.2 ) vs. 64 ( 14.3 ) , n.s . ) . There was no revision after 5 years . Conclusions In terms of clinical , radiological or general health outcomes for people who underwent TKA , the results of this study showed no clear advantage of mobile weight-bearing over the fixed weight-bearing prosthesis at the five-year follow-up . Level of evidence A prospect i ve study was performed to compare the clinical and radiological results of mobile- and fixed-bearing total knee arthroplasty  with specific attention to rotational alignment and range of motion . Sixty-one knees were assigned to total knee arthroplasty with either the NexGen LPS Flex fixed-bearing or with the NexGen LPS Flex mobile-bearing prosthesis . Postoperatively , knees were compared with regard to range of motion , clinical score , and radiographic findings . Rotational alignment of the femoral and tibial components was evaluated by computed tomography . The median follow-up period was 5.9 years ( range 2.1–8.8 years ) . Median postoperative Knee Society scores were 99 points ( 68–100 ) for the fixed-bearing group and 100 points ( 66–100 ) for the mobile-bearing group ( n.s . ) . The median postoperative flexion angles of 120 ° ( 90 ° –150 ° ) for the fixed-bearing group and 125 ° ( 90 ° –145 ° ) for the mobile-bearing group were not significantly different from each other ( n.s . ) . No knee required revision surgery due to wear of polyethylene or loosening of the component in either group . Computed tomography showed that 11 knees had rotational mismatches of more than 10 ° between the femoral and tibial components , but no significant difference was found in the postoperative extension and flexion angles or in the clinical score between the two treatment groups . Using the identical design for both fixed- and mobile-bearing prostheses , this prospect i ve , r and omized study did not show any clinical advantages of the mobile-bearing knee . Analysis of rotational alignment by CT scan did not reveal a particular advantage of the self-aligning mechanism of mobile-bearing implants
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 .