Should we reconsider all-polyethylene tibial implants in total knee replacement? A randomised controlled trial of the clinical effectiveness and cost-effectiveness of different knee prostheses: the Knee Arthroplasty Trial (KAT). Randomized clinical trial of rotating-platform and fixed-bearing total knee arthroplasty: no clinically detectable differences at five years. Problems With Cementless Total Knee Arthroplasty at 11 Years Followup Tibial component fixation in porous- and hydroxyapatite-coated total knee arthroplasty: a radiostereo metric evaluation of migration and inducible displacement after 5 years. Influence of polyethylene constraint on tibial component fixation in total knee arthroplasty: follow-up report after 5 years. The effect of Palamed® G bone cement on early migration of tibial components in total knee arthroplasty Prospective results of uncemented tantalum monoblock tibia in total knee arthroplasty: minimum 5-year follow-up in patients younger than 55 years. Five- to 12-year follow-up of a hydroxyapatite-coated, cementless total knee replacement in young, active patients. [Prospective randomized comparative study of early functional outcome of 2 knee joint endoprosthesis systems--rotation plateau versus fixed polyethylene inlay]. Navigated Cementless Total Knee Arthroplasty - Medium-Term Clinical and Radiological Results§ Reliability of templating with patient-specific instrumentation in total knee arthroplasty. Deep-Dish Congruent Tibial Component Use in Total Knee Arthroplasty: A Randomized Prospective Study Mobile and fixed-bearing (all-polyethylene tibial component) total knee arthroplasty designs. A prospective randomized trial. Comparison of a novel porous titanium construct (Regenerex®) to a well proven porous coated tibial surface in cementless total knee arthroplasty - A prospective randomized RSA study with two-year follow-up. Clinical results of the modular porous-coated anatomic (PCA) total knee arthroplasty with cement: a 5-year prospective study. 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.
The role of modular tibial implants in total knee replacement is not fully defined . We performed a prospect i ve r and omised controlled clinical trial using radiostereophotogrammetric analysis to compare the performance of an all-polyethylene tibia with a metal-backed cruciate-retaining condylar design , PFC-Sigma total knee replacement for up to 24 months . There were 51 patients who were r and omised into two treatment groups . There were 10 subsequent withdrawals , leaving 21 all-polyethylene and 20 metal-backed tibial implants . No patient was lost to follow-up . There were no significant demographic differences between the groups . At two years one metal-backed implant showed migration > 1 mm , but no polyethylene implant reached this level . There was a significant increase in the SF-12 and Oxford knee scores after operation in both groups . In an uncomplicated primary total knee replacement the all-polyethylene PFC-Sigma tibial prosthesis showed no statistical difference in migration from that of the metal-backed counterpart . There was no difference in the clinical results as assessed by the SF-12 , the Oxford knee score , alignment or range of movement at 24 months , although these assessment measures were not statistically powered in this study BACKGROUND In the late 1990s , new developments in knee replacement were identified as a priority for research within the NHS . The newer forms of arthroplasty were more expensive and information was needed on their safety and cost-effectiveness . OBJECTIVES The Knee Arthroplasty Trial examined the clinical effectiveness and cost-effectiveness of four aspects of knee replacement surgery : patellar resurfacing , mobile bearings , all-polyethylene tibial components and unicompartmental replacement . DESIGN This study comprised a partial factorial , pragmatic , multicentre r and omised controlled trial with a trial-based cost-utility analysis which was conducted from the perspective of the NHS and the patients treated . Allocation was computer generated in a 1 : 1 ratio using a central system , stratified by eligible comparisons and surgeon , minimised by participant age , gender and site of disease . Surgeons were not blinded to allocated procedures . Participants were unblinded if they requested to know the prosthesis they received . SETTING The setting for the trial was UK secondary care . PARTICIPANTS Patients were eligible for inclusion if a decision had been made for them to have primary knee replacement surgery . Patients were recruited to comparisons for which the surgeon was in equipoise about which type of operation was most suitable . INTERVENTIONS Patients were r and omised to receive a knee replacement  with the following : patellar resurfacing or no patellar resurfacing irrespective of the design of the prosthesis used ; a mobile bearing between the tibial and femoral components or a bearing fixed to the tibial component ; a tibial component made of either only high-density polyethylene ( ' all polyethylene ' ) or a polyethylene bearing fixed to a metal backing plate with attached stem ; or unicompartmental or total knee replacement . MAIN OUTCOME MEASURES The primary outcome was the Oxford Knee Score ( OKS ) . Other outcomes were Short Form 12 ; EuroQol 5D ; intraoperative and postoperative complications ; additional surgery ; cost ; and cost-effectiveness . Patients were followed up for a median of 10 years ; the economic evaluation took a 10-year time horizon , discounting costs and quality -adjusted life-years ( QALYs ) at 3.5 % per annum . RESULTS A total of 116 surgeons in 34 centres participated and 2352 participants were r and omised : 1715 in patellar resurfacing ; 539 in mobile bearing ; 409 in all-polyethylene tibial component ; and 34 in the unicompartmental comparisons . Of those r and omised , 345 were r and omised to two comparisons . We can be more than 95 % confident that patellar resurfacing is cost-effective , despite there being no significant difference in clinical outcomes , because of increased QALYs [ 0.187 ; 95 % confidence interval ( CI ) -0.025 to 0.399 ] and reduced costs ( -£104 ; 95 % CI -£630 to £ 423 ) . We found no definite advantage or disadvantage of mobile bearings in OKS , quality of life , reoperation and revision rates or cost-effectiveness . We found improved functional results for metal-backed tibias : complication , reoperation and revision rates were similar . The metal-backed tibia was cost-effective ( particularly in the elderly ) , costing £ 35 per QALY gained . CONCLUSIONS The results provide evidence to support the routine resurfacing of the patella and the use of metal-backed tibial components even in the elderly . Further follow-up is required to assess the stability of these findings over time and to inform the decision between mobile and fixed bearings . TRIAL REGISTRATION Current Controlled Trials IS RCT N45837371 . FUNDING This project was funded by the NIHR Health Technology Assessment programme and the orthopaedic industry . It will be published in full in Health Technology Assessment ; Vol . 18 , No. 19 . See the NIHR Journals Library website for further project information BACKGROUND For some surgeons , rotating-platform total knee design s are an intellectually appealing option to use for total knee arthroplasty because of the contention that they can self-align and accommo date small mismatches in the rotational position of the tibial and femoral components . We carried out a r and omized clinical trial to determine if a posterior-stabilized , rotating-platform knee design provided better maximum knee flexion , better function , or better durability at five years of follow-up when compared with a fixed-bearing design . METHODS This r and omized clinical trial of 240 primary total knee arthroplasties involved a single type of distal femoral implant ( posterior-stabilized ) and three different types of tibial implant ( all-polyethylene fixed-bearing , modular-metal-backed fixed-bearing , and rotating-platform ) . The three tibial implant groups were balanced dynamically with a computerized r and omization process that accounted for patient age , sex , and body mass index ; surgeon ; and implant type . Patients returned for examination and radiographs at three months , one year , two years , and five years postoperatively . RESULTS Knee range of motion was not significantly different among the all-polyethylene , modular-metal-backed , and rotating-platform tibial component groups at two years ( mean , 111 ° , 111 ° , and 110 ° , respectively ) or five years ( mean , 110 ° , 109 ° , and 109 ° , respectively ) . Function , as measured with Knee Society scores , was not significantly different among the all-polyethylene , modular-metal-backed , and rotating-platform groups at two years ( mean , 90 , 91 , and 91 points , respectively ) or five years ( mean , 88 , 89 , and 88 points , respectively ) . Stair-climbing scores were not significantly different among the three groups at two years ( mean , 39 , 40 , and 39 points , respectively ) or five years ( mean , 37 , 40 , and 36 points , respectively ) . There were four revisions : one in the all-polyethylene group ( patellar fracture ) , two in the modular-metal-backed group ( aseptic loosening ) , and one in the rotating-platform group ( deep infection ) . CONCLUSIONS In this r and omized clinical trial , the rotating-platform total knee design was reliable and durable but did not provide better maximum knee flexion , better function , or better durability at five years postoperatively when compared with a posterior-stabilized , fixed-bearing design incorporating either an all-polyethylene or a modular-metal-backed tibial component One hundred two patients with 131 consecutive cementless total knee arthroplasties that retained the posterior cruciate ligament were followed up prospect ively . The average age of the patients was 58 years ( range , 32–75 years ) . The mean followup on the surviving knee arthroplasties was 11 years ( range , 7–16 years ) . The patellar component was metal-backed in the first 112 ( 85 % ) knees , cementless all-polyethylene in the last 17 ( 13 % ) knees , and two knees had a prior patellectomy . Forty-four metal-backed patellar components ( 48 % ) were revised ; nine were loose , and 35 had polyethylene wear through . Thirteen femoral components ( 12 % ) were revised because of femoral abrasion from a failed metal-backed patellar component . No other femoral component was revised , loose , or had osteolysis develop . Nine ( 8 % ) tibial components had failure of ingrowth ; eight have been revised . Partial radiolucencies occurred in 53 % of the tibias . Thirteen ( 12 % ) small osteolytic lesions developed , all around screws or screw holes in the tibial components . At an average of 11 years followup , cementless fixation yielded mixed results : cementless femoral fixation was excellent and metal-backed patellar components had a 48 % patellar revision rate . Cementless tibial components had an 8 % aseptic loosening rate and a 12 % incidence of small osteolytic lesions . Based on these results , the authors have ab and oned cementless fixation in total knee arthroplasty A total of 51 knees ( 45 patients ) with osteoarthrosis were stratified in a r and omized study to receive a hydroxyapatite-coated Freeman-Samuelson ( FS HA ) or a porous-coated Miller-Galante II ( MG II ) uncemented total knee arthroplasty . Repeated clinical , radiographic  , and  radiostereometric analysis (  RSA ) evaluations of the tibial components were done for 5 years . The clinical outcome was equal at the 5-year follow-up ( mean Hospital for Special Surgery score , 93 ) . St and ard radiographs displayed more zones around the tibial stem in the MG II group . RSA revealed that the FS HA components migrated less ( smaller maximum total point motion and maximum subsidence ) after 5 years and showed less inducible displacements at the 1-year follow-up . The stability of the implants obtained is equal to or better than cemented implants after 5 years . Key words : knee prosthesis , cementless , hydroxyapatite , radiostereometry , inducible displacement The influence of articulating surface design of AMK total knee prosthesis ( DePuy , Johnson & Johnson ) on migration and radiographic outcome at 5 years was evaluated . The knees were r and omly allocated to receive a flat or a concave insert with retention of the posterior cruciate ligament when preoperative deformity was less severe and either a concave or a posterior-stabilized insert with resection of the posterior cruciate ligament when deformity was more pronounced . In 64 knees , migration was measured with radiostereometry . The posterior-stabilized component displayed more varus-valgus tilting than the concave insert . Other statistically significant differences in migration were not seen . Radiolucent lines were frequently seen without differences between prosthesis groups Abstract Objective : Migration of the tibial component in total knee arthroplasty ( TKA ) is subject of many studies using roentgen stereophotogrammetric analysis ( RSA ) . In previous studies of cemented and uncemented tibial components , high migration values were found . Improvements in cementing technique , prosthetic design and pre-coating techniques reduced these values as shown in more recent studies . Material and subjects : A total of 35 patients were initially included in the study and operated on between 12/1999 and 10/2000 . All patients received a NexGen ® TKA cemented into the proximal tibia using Palamed ® G bone cement . The implants and the tibial metaphysis were marked with st and ard tantalum markers . Radiostereometric analysis was performed post-operatively and after 3 , 6 and 12 months using a st and ard digital radiostereometric analysis . Functional parameters were assessed using the Knee Society Score ( KSS ) clinical rating system . Results : There were no complications and failures within the first year . After 1 year radiostereometric measurements of the translational parameters along and the rotational parameters around the x- , y- and z-axis revealed : X-Trans –0.19 mm , Y-Trans + 0.02 mm , Z-Trans + 0.08 mm , X-Rot + 0.26 ° , Y-Rot –0.35 ° , Z-Rot + 0.09 ° . The maximum total point motion was + 0.96 mm and the mean maximum subsidence was –0.23 mm . Except for anterior-posterior , medio-lateral stability and extension leg all endpoints of the KSS clinical rating system showed a significant improvement . Conclusions : After 12 months , the use of Palamed ® G bone cement in total knee arthroplasty was demonstrated to be safe . Both the clinical and radiostereometric results were good and comparable to the results reported in other RSA studies in cemented total knee arthroplasty A significant increase in younger patients undergoing total knee arthroplasty raises the theoretical concern for revision secondary to micromotion and fixation failure with cemented components . We prospect ively studied 100 consecutive tantalum monoblock uncemented tibial components and 312 concurrent cemented controls . Patients younger than 55 years with adequate bone stock were enrolled . This cementless patient group was younger and had higher preoperative functional status . Prostheses were posterior-substituting uncemented femoral and tibial components with a cemented patellar button .  Knee Society pain and function scores and radiographs were obtained , and a cost analysis was performed . Knee Society scores were excellent and equivalent beyond 6 months . There was no significant difference in perioperative blood loss , complication rates , or cost . There was a significant decrease in operative time in the uncemented group . Radiographs revealed no failures of ingrowth at last follow-up . There were 3 uncemented group failures , but none were due to failure of fixation . The use of a porous tantalum tibia at minimum 5 years has yielded promising clinical and radiographic results in a younger patient population We carried out a prospect i ve study of 118 hydroxyapatite-coated , cementless total knee replacements in patients who were < /= 55 years of age and who had primary ( 92 ; 78 % ) or post-traumatic ( 26 ; 22 % ) osteoarthritis . The mean period of follow-up was 7.9 years ( 5 to 12.5 ) . The Knee Society clinical scores improved from a pre-operative mean of 98 ( 0 to 137 ) to a mean of 185 ( 135 to 200 ) at five years , and 173 ( 137 to 200 ) at ten years . There were two revisions of the tibial component because of aseptic loosening , and one case of polyethylene wear requiring further surgery . There was no osteolysis or progressive radiological loosening of any other component . At 12 years , the overall rate of implant survival was 97.5 % ( excluding exchange of spacer ) and 92.1 % ( including exchange of spacer ) . Cementless total knee replacement can achieve excellent long-term results in young , active patients with osteoarthritis . In contrast to total hip replacement , polyethylene wear , osteolysis and loosening of the prosthesis were not major problems for these patients , although it is possible that this observation could change with longer periods of follow-up AIM Different systems are used for total knee arthroplasty ( TKA ) . Compared were a press-fit femur condyle replacement system with fixed tibial PE-inlay versus a rotating tibia component system with an emphasis on the early functional results . METHOD Patient selection and the use of the  Knee Society Score for this r and omized and prospect i ve study were based on the directives for TKA of the german Society for Orthopaedic and Trauma Surgery ( DGOT ) . We examined the patients post-operatively after 1 week , 2 weeks , 6 weeks , 3 months , 6 months , and 1 year . RESULTS After 6 weeks an increase of the total knee score could be seen in both groups . The total knee score of the rotating tibia component  increased from 93.96 pre-operatively to 113.57 after 6 weeks , to 139.82 after 3 months , to 154.32 after 6 months , and to 159.65 after one year . The total score with the fixed PE-inlay increased from 79.75 to 111.5 after 6 weeks , to 128.25 after 3 months , to 134.08 after 6 months , and to 130.08 after one year . CONCLUSION After 6 weeks the implant with the rotating tibia component showed a lasting higher score as compared to the implant with a fixed PE-inlay component using the same early rehabilitation and mobilization techniques Purpose : The objective of this prospect i ve study was to evaluate the medium-term clinical and radiological results after navigated cementless implantation , without patella resurfacing , of a total knee endoprosthesis with tibial and femoral press-fit components , with a focus on survival rate and clinical outcome . The innovation is the non-cemented fixation together with the use of a navigation system . Scope and Methods : Sixty patients with gonarthrosis were included consecutively in this study . In all cases , the cementless Columbus total knee endoprosthesis with a coating out of pure titanium was implanted , using a navigation system . The Knee Society Score showed a statistically significant increase from 75 ( ± 21.26 ) before surgery to 180 ( ± 16.15 ) after a mean follow-up of 5.6 ( ± 0.25 ) years . The last radiological examination revealed no osteolysis . No radiolucent lines were seen at any time in the area of the femoral prosthetic components . In the tibial area , radiolucent lines were seen in 24.4 % of the cases , mostly in the distal uncoated part of the stem . During follow-up , no prosthesis had to be replaced because of aseptic loosening while in 2 cases revision surgery was necessary due to septic loosening and in 1 case due to unexplainable pain . Results and Conclusions : Navigated cementless implantation of the Columbus total knee endoprosthesis yielded good clinical and radiological results in the medium term . The excellent radiological osteointegration of the prosthetic components , coated with a microporous pure titanium layer and implanted with a press-fit technique , should be emphasized Magnetic resonance imaging ( MRI ) or computed tomography-based patient-specific instrumentation ( PSI ) may allow for reliable alignment and fewer outliers when compared with conventionally instrumented total knee arthroplasty ( TKA ) . However , some authors have suggested that frequent intraoperative surgeon-directed changes may still be required . This study evaluated the accuracy of  PSI  to predict component sizing and alignment during TKA . A total of 84 patients ( 89 knees ) who underwent a TKA using a PSI system were evaluated . An MRI-based preoperative plan of every knee was provided and approved by the surgeons . This demonstrated the proposed prosthetic component alignment , as well as the femoral , tibial , and bearing insert component size and position . Intraoperative changes to these components were prospect ively recorded and compared with the computerized preoperative plan . Major changes were defined as any changes in femoral or tibial resection , size , and position of the components . Minor changes were defined as any change in the size of the polyethylene bearing insert . The preoperative plan was able to correctly predict the size of the implanted tibial and femoral component in 93 and 95.5 % of the cases , respectively . Thirteen major intraoperative changes were made . In one knee , the proposed femoral resection was not acceptable ( because of the presence of significant amount of osteophytes ) and was ab and oned in favor of a manual extramedullary guide . In another patient , the proposed femoral and tibial components were upsized . In two other patients , the femoral components were downsized , in four patients , the tibial components were downsized , and in another patient , it was upsized . There were also 16 minor changes , which included 2-mm upsizing of the polyethylene liner in 13 knees and 4-mm upsizing in 3 knees . Surgical experience is necessary to recognize improper component size , incorrect surgical resection , or nonideal alignment when performing TKA using PSI . The authors believe that the design and manufacture of PSI combined with a comprehensive templating result ed in excellent intraoperative concordance of the preoperative plan at the default setting s with minimal changes One hundred seventy-six patients with osteoarthritis of the knee were r and omized prospect ively into two groups . In both groups the posterior cruciate ligament was released from its femoral attachment . In one group a posterior stabilized tibial component was used whereas in the other group a deep-dish tibial polyethylene component was inserted ( Genesis II ) . The surgical and perioperative technique was identical in both groups and all the implants were cemented to their respective bones . Patients began range of motion exercises within the first few hours after surgery and were allowed weightbearing to tolerance beginning on the first postoperative day . At followup there was no statistical difference in the mean range of flexion ( approximately 116 ° ) , ability to ascend and descend stairs in a bipedal manner ( 80 % ) , pain scores , knee scores ( 94 points ) , stability , or the lack of anterior knee pain . Postoperative implant alignment in the sagittal and coronal planes and on Merchant skyline views was excellent in both groups . There was only one lateral release required and that was in one patient who received a deep-dish component . Using deep-dish implant obviates the need to resect intercondylar femoral bone , decreasing the potential for fracture and maximizing bone volume should revision be necessary in the future 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 Regenerex is a novel porous titanium construct with a three-dimensional porous structure and biomechanical characteristics close to that of normal trabecular bone . The aim of this study was to compare this novel construct to a well-proven porous plasma sprayed tibial ( PPS ) implant after total knee arthroplasty . METHODS Sixty-one patients scheduled for an uncemented TKA were r and omized to receive either a novel highly porous titanium construct Regenerex or the PPS tibial component . Radiostereometric analysis of the tibial components was performed postoperatively and at three , six , 12 , and 24months with measurements of migration ( segment motion and maximum total point motion ( MTPM ) ) . RESULTS Knee and function scores improved significantly from preoperatively to two-year follow-up . For both the Regenerex and the PPS the majority of migration appeared during the first three months and then stabilized . No statistically significant differences in MTPM were found in any follow-up between three and 24months . The Regenerex group had a lower migration rate between 12 and 24months compared with the PPS implants ( p=0.03 ) but the PPS group had an initial significantly lower subsidence ( p=0.04 ) . CONCLUSION In conclusion the Regenerex implant could prove an effective scaffold material for coating of uncemented implants but did no better than the PPS component at 24months of follow-up . Clinical Trials.gov identifier : NCT01936415 Our study examines the clinical , radiographic , and patient satisfaction outcome of the cemented Modular Porous-Coated Anatomic ( PCA ) total knee arthroplasty with a minimum 5-year follow up . All data were gathered prospect ively and consecutively . Patient satisfaction was assessed with a self-administered survey . Statistical analysis examined the effect of 17 patient factors , 19 surgical factors , and postoperative continuous passive motion use on range of motion ( ROM ) and HSS scores at 2 years . Seventy-eight Modular PCA arthroplasties performed by 9 orthopedic surgeons on 71 patients between January 1988 and November 1989 are reported in this study .  Preoperative HSS scores averaged 51.2 and improved to an average of 89 at 1 and 2 years , and 86 at 5 years after surgery ( 90 % good or excellent ) . ROM changed after surgery through improvement in preoperative knee flexion contracture , but not in increased knee flexion . One patient underwent reoperation for patellar instability , and one patient 's arthroplasty was revised at 53 months for late instability . The total reoperation rate for any reason was 7.7 % . Zonal analysis for progressive radiolucency at the bone-cement interface showed increasing frequency of narrow ( < 1 mm ) radiolucencies concentrated on the anterior and medial aspect of the tibial tray . Ninety-eight percent of patients responded to an outcome question naire , and 96 % rated themselves improved . The Kaplan-Meier probability of an implant surviving without loosening at 5 years was 100 % . The Modular PCA TKA has a low incidence of patellofemoral problems , is clinical ly successful , and results are stable at a minimum 5-year follow-up examination 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
Finally , with use of a variety of vali date d measures , there was no difference between the two groups in terms of functional status at two , eight , and ten years , regardless of the measure used .
A less expensive all-polyethylene component as part of a total knee arthroplasty has results equivalent to those obtained with a cemented metal-backed tibial component .
BACKGROUND The cost of the implant as part of a total knee arthroplasty accounts for a substantial portion of the costs for the overall procedure : all-polyethylene tibial components cost considerably less than cemented metal-backed tibial components .
We performed a systematic review of the literature to determine whether the clinical results of lower-cost all-polyethylene tibial components were comparable with the results of a more expensive metal-backed tibial component .