title: Postoperative clodronate decreases prosthetic migration: 4–year follow-up of a randomized radiostereometric study of 50 total knee patients Fixation of high-flexion total knee prostheses: five-year follow-up results of a four-arm randomized controlled clinical and roentgen stereophotogrammetric analysis study. Hydroxyapatite-Enhanced Tibial Prosthetic Fixation Similar early migration when comparing CR and PS in Triathlon™ TKA: A prospective randomised RSA trial. The effect of Palamed® G bone cement on early migration of tibial components in total knee arthroplasty 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. Cemented tibial component fixation performs better than cementless fixation Celecoxib does not appear to affect prosthesis fixation in total knee replacement The beneficial effect of hydroxyapatite lasts Local peroperative treatment with a bisphosphonate improves the fixation of total knee prostheses: A randomized, double-blind radiostereometric study of 50 patients Inferior performance of Boneloc bone cement in total knee arthroplasty: a prospective randomized study comparing Boneloc with Palacos using radiostereometry (RSA) in 19 patients. Hydroxyapatite coating versus cemented fixation of the tibial component in total knee arthroplasty: prospective randomized comparison of hydroxyapatite-coated and cemented tibial components with 5-year follow-up using radiostereometry. Migration of a cemented fixed-bearing, polished titanium tibial baseplate (Genesis II) at ten years : a radiostereometric analysis. Proximally cemented versus uncemented Freeman-Samuelson knee arthroplasty. A prospective randomised study. Survival of knee arthroplasties. A nation-wide multicentre investigation of 8000 cases. Effect of a cooled saw blade on prosthesis fixation. Randomized radiostereometry of 33 knee cases. Early Inducible Displacement of Tibial Components in Total Knee Prostheses Inserted with and without Cement. A Randomized Study with Roentgen Stereophotogrammetric Analysis* Fixation of the tibial component using CMW-1 or Palacos bone cement with gentamicin: Similar outcome in a randomized radiostereometric study of 51 total knee arthroplasties Mobile Bearings Do Not Improve Fixation in Cemented Total Knee Arthroplasty Increased varus-valgus tilting of screw-fixated knee prostheses. Stereoradiographic study of uncemented versus cemented tibial components. The effect of tourniquet use on fixation quality in cemented total knee arthroplasty a prospective randomized clinical controlled RSA trial. Ceramic coating improves tibial component fixation in total knee arthroplasty. The stability of three different cementless tibial components. A randomized radiostereometric study in 45 knee arthroplasty patients. VersaBond bone cement prospective randomized study of the clinical properties of a new bone cement in total knee replacement. Absence of a Tourniquet Does Not Affect Fixation of Cemented TKA: A Randomized RSA Study of 70 Patients.
abstract: Background We have previously reported that 6 months of oral treatment with clodronate reduced the migration of the NexGen total knee prosthesis during the first postoperative year , as measured by  radiostereometry ( RSA ) . We now report the 4-year results . Methods This was a double-blind r and omized study , using RSA with maximal total point motion ( MTPM ) . Results With analysis according to the “ intention to treat ” principle , the only remaining difference between the groups at 4 years was reduced rotation around the transverse axis ( a secondary variable ) in the clodronate group . However , 3 patients ( all clodronate )  did not take any tablet after surgery . If they are excluded , there was an almost statistically significant difference between the groups at 4 years regarding MTPM from baseline , with the clodronate group showing 25 % less migration . From 1 to 4 years , there was no difference in migration rate by MTPM , but there was a continuous increase in rotation around the transverse axis in the controls , which differed from the clodronate group . There were no cases of aseptic loosening . 2 patients had migration of more than 1.3 mm from baseline to 4 years ; neither of them had taken clodronate . The others had migration of less than 0.9 mm . Interpretation Because migration was clearly reduced by clodronate during the first postoperative year , and there was still a difference at 4 years when analyzed per protocol , it appears likely that this treatment can diminish the risk of loosening . The difference in the number of outliers also points in this direction , and may be more relevant than mean migration values BACKGROUND High-flexion total knee arthroplasty was introduced to meet the dem and s of daily activity requiring increased knee flexion . However , concerns have been raised regarding the fixation of high-flexion total knee arthroplasty components and increased rates of loosening have been reported . To date , migration , and thus fixation , of high-flexion total knee arthroplasty components has not been analyzed and the preferential bearing type ( mobile or fixed ) is unknown . METHODS Of eighty-six consecutive eligible patients , seventy-four patients ( seventy-eight knees ) scheduled for total knee arthroplasty were r and omized to one of four  Legacy Posterior Stabilized ( LPS ) total knee prosthesis design s : ( 1 ) LPS-Flex mobile , ( 2 ) LPS-Flex fixed , ( 3 ) LPS mobile , and ( 4 ) LPS fixed . The primary outcome was component migration measured with use of Roentgen stereophotogrammetric analysis , and secondary outcomes were postoperative knee flexion and extension and Knee Society Score . Patients were evaluated postoperatively at six , twelve , twenty-six , and fifty-two weeks and annually thereafter . At the five-year follow-up , eight patients had died and two patients were lost to follow-up . Seventy-seven tibial and forty-two femoral components were suitable for migration measurements . RESULTS The overall five-year migration of the seventy-seven tibial components was not significantly different among the four total knee prosthesis design s ( compared with the LPS fixed design , the range of overall mean differences for the other three design s was 0.02 to 0.25 mm ) and migration was comparable at the two and five-year follow-up . Migration stabilized in all but three components ( two LPS-Flex mobile and one LPS fixed ) ; one of these components has already been revised and was aseptically loose . The overall five-year migration of the forty-two femoral components was comparable among the four design s ( compared with the LPS fixed design , the range of overall mean differences for the other three design s was 0.01 to 0.18 mm ) and was similar at two and five years postoperatively . One femoral component ( LPS-Flex mobile ) migrated excessively . In patients who had a mean postoperative flexion of ≥ 125 ° or a maximum flexion of ≥ 135 ° during the one to five-year follow-up period , migration of high-flexion components was comparable with that of conventional components and indicative of appropriate fixation . Postoperative flexion , extension , Knee Society Score , and Knee Society Score function were comparable during the five-year follow-up period and at the two and five-year follow-up . CONCLUSIONS The LPS-Flex total knee prosthesis with either a mobile or a fixed bearing had migration comparable that of with its conventional counterpart and is expected to have similar ( excellent ) long-term survival in these patients . LEVEL OF EVIDENCE Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence Sixty-two knees ( 60 patients ) were r and omized to four noncemented groups . In Groups 1 , 3 , and 4 , the bone cuts were made with a cooled saw blade . In Group 1 , 15 patients were operated on with the porous coated Osteonic 7000 tibial component . In Group 2 , 15 patients were operated on with the same tibial component as in Group 1 but with the use of a st and ard saw blade . In Group 3 , 16 patients were operated on with the hydroxyapatite-coated Osteonic tibial component , and in Group 4 , 16 patients were operated on with the hydroxyapatite Duracon tibial component . All patients were followed up clinical ly and with roentgenstereometric analysis . There were no differences among the groups regarding clinical outcome . One knee was revised ( Group 2 ) after 1 year because of loosening of the tibial component . The maximum migration at 1 year was 1.7 mm in Group 1 , 1.9 mm in Group 2 , 1.3 mm in Group 3 , and 1 mm in Group 4 . At the 2-year followup , the migrations were 1.8 mm , 1.5 mm , 1.4 mm , and 1 mm in Groups 1 , 2 , 3 , and 4 , respectively . The inducible displacement that occurred at 1 year was 0.6 mm in Group 1 , 0.5 mm in Group 2 , 0.4 mm in Group 3 , and 0.4 mm in Group 4 . The hydroxyapatite coating had a strong positive effect on the tibial component fixation . No prosthesis in the hydroxyapatite groups showed continuous migration OBJECTIVES The objective of this study was to compare the early migration of the cruciate retaining and posterior stabilising versions of the recently introduced Triathlon ™ total knee system , with a view to predicting long term fixation performance . METHODS Sixty patients were prospect ively r and omised to receive either Triathlon ™ posterior stabilised cemented knee prosthesis or Triathlon ™ cruciate retaining cemented knee prosthesis . Tibial component migration was measured by radiostereometric analysis postoperatively and at three months , one year and two years . Clinical outcome was measured by the American Knee Society Score and Knee Osteoarthritis and Injury Outcome Score . RESULTS There were no differences in rotation around the three coordinal axes or in the maximum total point motion ( MTPM ) during the two year follow-up . The posterior stabilised prosthesis had more posterior-anterior translation at three months and one year and more caudal-cranial translation at one year and two years . There were no differences in functional outcome between the groups . CONCLUSION The tibial tray of the Triathlon ™ cemented knee prosthesis showed similar early stability . LEVEL OF EVIDENCE Level I. ARTICLE SUMMARY Article focus : This was a prospect i ve r and omised trial aim ing to compare the single radius posterior stabilised ( PS ) Triathlon ™ total knee arthroplasty ( TKA ) to the cruciate retaining Triathlon ™ TKA system with regard to fixation . Strengths and limitations of this study : Strength of this study was that it is a r and omised prospect i ve trial using an objective measuring tool . The sample size of 25 - 30 patients was reportedly sufficient for the screening of implants using RSA [ 1 ] . TRIAL REGISTRATION Clinical Trials.gov Identifier : NCT00436982 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 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 Background The question whether the tibial component of a total knee arthroplasty  should be fixed to bone with or without bone cement has not yet been definitely answered . We studied movements between the tibial component and bone by radiostereometry ( RSA ) in total knee replacement ( TKR ) for 3 different types of fixation : cemented fixation ( C-F ) , uncemented porous fixation ( UC-F ) and uncemented porous hydroxyapatite fixation ( UCHA-F ) . Patients 116 patients with osteoarthrosis , who had 146 TKRs , were included in 2 r and omized series . The first series included 86 unilateral TKRs stratified into 1 of the 3 types of fixation . The second series included 30 patients who had simultaneous bilateral TKR surgery , and who were stratified into 3 subgroups of pairwise comparisons of the 3 types of fixation . Results After 5 years 2 knees had been revised , neither of which were due to loosening . 1 UCHA-F knee in the unilateral series showed a large and continuous migration and a poor clinical result , and is a pending failure . The C-F knees rotated and migrated less than UC-F and UCHA-F knees over 5 years . UCHA-F  migrated less than UC-F after 1 year . Interpretation Cementing of the tibial component offers more stable bone-implant contact for 5 years compared to uncemented fixation . When using uncemented components , however , there is evidence that augmenting a porous surface with hydroxyapatite may mean less motion between implant and bone after the initial postoperative year Background and purpose After joint replacement , a repair process starts at the interface between bone and cement . If this process is disturbed , the prosthesis may never become rigidly fixed to the bone , leading to migration— and with time , loosening . Cox-2 inhibitors are widely used as postoperative analgesics , and have adverse effects on bone healing . This could tamper prosthesis fixation . We investigated whether celecoxib , a selective Cox-2 inhibitor , increases prosthesis migration in total knee replacement ( TKR ) . Methods 50 patients were r and omized to either placebo or celecoxib treatment , 200 mg twice daily , for 3 weeks after TKR  ( NexGen ; Zimmer ) . Maximum total point motion ( MTPM ) of the tibial component was measured after 2 years using radiostereometric analysis ( RSA ) . In addition , range of motion , pain , and , subjective outcome were evaluated . Results No differences in prosthesis migration , pain scores , range of motion , and subjective outcome were found after 2 years . Confidence intervals were narrow . Interpretation It is unlikely that Celecoxib increases the risk of loosening , and it may be used safely in conjunction with TKR Background and purpose In contrast to early migration , the long-term migration of hydroxyapatite- ( HA- ) coated tibial components in TKA has been scantily reported . This r and omized controlled trial investigated the long-term migration measured by radiostereometric analysis ( RSA ) of HA-coated , uncoated , and cemented tibial components in TKA . Patients and methods 68 knees were r and omized to HA-coated ( n = 24 ) , uncoated ( n = 20 ) , and cemented ( n = 24 ) components .  All knees were prospect ively followed for 11–16 years , or until death or revision .  RSA  was used to evaluate migration at yearly intervals . Clinical and radiographic evaluation was according to the Knee Society system . A generalized linear mixed model ( GLMM , adjusted for age , sex , diagnosis , revisions , and BMI ) was used to take into account the repeated-measurement design . Results The present study involved 742 RSA analyses . The mean migration at 10 years was 1.66 mm for HA , 2.25 mm for uncoated and 0.79 mm for the cemented group ( p < 0.001 ) . The reduction of migration by HA as compared to uncoated components was most pronounced for subsidence and external rotation . 3 tibial components were revised for aseptic loosening ( 2 uncoated and 1 cemented ) , 3 for septic loosening ( 2 uncoated and 1 cemented ) , and 1 for instability ( HA-coated ) . 2 of these cases were revised for secondary loosening after a period of stability : 1 case of osteolysis and 1 case of late infection . There were no statistically significant differences between the fixation groups regarding clinical or radiographic scores .  Interpretation HA reduces migration of uncemented tibial components . This beneficial effect lasts for more than 10 years . Cemented components showed the lowest migration . Longitudinal follow-up of TKA with RSA allows early detection of secondary loosening Background Postoperative migration of a joint prosthesis is related to the risk of late loosening . We have previously reported that oral treatment with clodronate reduced migration of the cemented NexGen total knee prosthesis during the first postoperative year , as measured by radiostereometry ( RSA ) . Oral bisphosphonate treatment is sometimes unpleasant , and local treatment will enable higher local concentrations . We now report the results of local peroperative treatment with another bisphosphonate , ib and ronate , with the same prosthesis . Methods This is a double-blind , r and omized study of 50 patients using RSA with maximal total point motion ( MTPM ) as primary effect variable . 1 mg ib and ronate ( 1 mL ) or 1 mL saline was applied to the tibial bone surface 1 min before cementation . RSA examination was done on the first postoperative day , and at 6 , 12 , and 24 months . Results One ib and ronate-treated patient died of unrelated causes , and 1 control patient refused to come for follow-up , leaving 24 patients in each group for analysis . There were no cases of aseptic loosening . By repeated measures ANOVA , migration ( MTPM ) was reduced by local application of ib and ronate ( p = 0.006 ) . The effect was most pronounced at 6 months , with a reduction from 0.45 to 0.32 mm ( 95 % CI for reduction : 0.04–0.21 mm ) . At 12 months , the migration from the postoperative examination was reduced from 0.47 to 0.36 mm ( 95 % CI for reduction : 0.02–0.20 mm ) . At 24 months , the reduction was from 0.47 to 0.40 mm ( 95 % CI : -0.01–0.16 mm ) . Interpretation This is the first study to show improvement of prosthesis fixation by local pharmacological treatment in humans . The treatment appears to be safe , cheap , and easy to perform . However , the improvement in postoperative stability was not greater than with systemic clodronate treatment We compared Boneloc bone cement with conventional cement ( Palacos ) in fixating the tibial component during 2 - 5 years in 19 patients with gonarthrosis undergoing total knee arthroplasty in a prospect i ve r and omized study .  Boneloc displayed significantly larger migration , subsidence and lift-off than Palacos . The difference was identifiable already within 3 months postoperatively , but became significant at 12 months . In the Boneloc group , all components showed subsidence of the posterior part and lift-off of the anterior part of the tibial component , whereas in the Palacos group , the locations of subsidence and lift-off were evenly distributed about the edge of the implant . At 5 years , both Boneloc knees so far investigated were clinical failures with high migration rates . We conclude that , even in total knee arthroplasty , there is a substantial risk that Boneloc leads to inferior clinical results , but later than in hip replacements Fifty-three consecutive patients ( 57 knees ; mean age , 69 years ) entered a prospect i ve r and omized study to compare the fixation of hydroxyapatite (HA)-coated ( 29 knees ) with cemented ( 28 knees ) tibial components in the Tricon II total knee arthroplasty . The quality of the fixation during 5 years postoperatively was evaluated with radiostereometric analysis ( RSA ) . Three HA-coated implants were revised : 2 owing to infection , and 1 owing to early delamination of the coating and clinical loosening . Eight patients ( 9 knees ) died , 1 patient sustained a stroke  , and 1 patient refused investigations after 1 year . In the 40 patients ( 19 HA-coated , 21 cemented ) remaining at 5 years , the magnitude of the micromotion between the HA-coated and cemented groups did not differ . The HA-coated implants displayed most of the migration within the initial 3 months then stabilized , whereas the cemented implants showed an initially lower , but over time continuously increasing migration . Between 1 and 2 years , 4 of 24 HA-coated and 10 of 23 cemented implants  migrated > 0.2 mm and were categorized unstable , which has been shown to have a prognostic value as regards future aseptic loosening . Progressive radiolucent lines developed in 2 cemented knees , which both were categorized unstable . If HA-coated implants can sustain the forces that threaten the fixation in the early period after implantation , a strong and enduring fixation may be obtained AIMS The purpose of the present study was to examine the long-term fixation of a cemented fixed-bearing polished titanium tibial baseplate ( Genesis ll ) . PATIENTS AND METHODS Patients enrolled in a previous two-year prospect i ve trial ( n = 35 ) were recalled at ten years . Available patients ( n = 15 ) underwent radiostereometric analysis ( RSA ) imaging in a supine position using a conventional RSA protocol . Migration of the tibial component in all planes was compared between initial and ten-year follow-up . Outcome scores including the Knee Society Score , Western Ontario and McMaster Universities Arthritis Index , 12-item Short Form Health Survey , Forgotten Joint Score , and University of California , Los Angeles Activity Score were recorded . RESULTS At ten years , the mean migration of the tibial component was less than 0.1 mm and 0.1 ° in all planes relative to the post-operative RSA exam . Maximum total point movement increased with time ( p = 0.002 ) from 0.23 mm ( sd 0.18 ) at six weeks to 0.42 mm ( sd 0.20 ) at ten years . CONCLUSION The low level of tibial baseplate migration found in the present study correlates to the low rate of revision for this implant as reported in individual studies and in joint replacement registries . TAKE HOME MESSAGE Overall , the implant was found to be well fixed at ten years , supporting its continued clinical use and the predictive power of RSA for determining long-term fixation of implants . Cite this article : Bone Joint J 2016;98-B:616 - 21 We studied the effect of a layer of cement placed under the tibial component of Freeman-Samuelson total knee prostheses  with a metal back and an 80 mm intramedullary stem , using roentgen stereophotogrammetry to measure the migration of the tibial component during one year in 13 uncemented and 16 cemented knees . The addition of cement produced a significant reduction in migration at one year , from a mean of 1.5 mm to one of 0.5 mm ( p less than 0.01 ) , including a significant reduction in pure subsidence . One year postoperatively the clinical results were similar between the groups , but , at three years , one uncemented knee had required revision A prospect i ve nation-wide study of  knee arthroplasty  has been under way in Sweden since October 1975 . By the end of 1983 , 4505 arthroplasties for osteoarthritis and 3495 for rheumatoid arthritis had been recorded and review ed one , three and six years after the operation . Using actuarial methods , the probability of the prosthesis remaining in situ after six years was calculated . In osteoarthritis this probability ranged from 65 % for hinged prostheses to 90 % for medial compartment prostheses . Two- and three-compartment prostheses produced intermediate results with 87 % survival . In rheumatoid arthritis the probability varied from 72 % for medial compartment prostheses to 90 % for two- and three-compartment prostheses . The main reason for failure was loosening of the components , the second most common was infection . The probability of revision for infection by six years was 2 % in osteoarthritis and 3 % in rheumatoid arthritis . Most revisions were to a three-compartment prosthesis .  Knee fusion at primary revision was required in 2 % of the cases at six years Tibial migration in 33 cementless total knee replacements , which were performed with a cooled saw blade vs. a conventional blade  , was studied in a r and omized prospect i ve study using roentgen stereophotogrammetric analysis ( radiostereometry ) . All cases were clinical ly successful after 2 years and inducible displacement was smaller in the group operated with the cooled saw blade . This group also had a tendency towards less continuous migration The  fixation of tibial components r and omized to insertion with or without cement in  twenty-six knees was examined for inducible displacement at six weeks and one year postoperatively with use of roentgen stereophotogrammetric analysis . Furthermore , migration was studied during the first two postoperative years . Inducible displacement was found in all knees at both the six-week and the one-year follow-up examination , but no differences were detected with respect to the type of fixation ( p > 0.05 ) . All tibial components  migrated for as long as one year postoperatively , after which most stabilized . No difference was found between the groups with respect to migration during the first two years postoperatively ( p > 0.05 ) , with the exception of subsidence of the component , which was found to be 0.0 ± 0.1 millimeter ( mean and st and ard error of the mean ) for the components inserted with cement and 0.5 ± 0.1 millimeter for the components inserted without cement ( p < 0.01 ) . Migration after one year was the same for both groups . We found a relationship between inducible displacement at six weeks and at one year as well as one between inducible displacement and migration at one year . To our knowledge , the present study is the first in which the micromotion of an interference-fit prosthesis was found to be similar to that of a device inserted with cement . The results of the present study emphasize the importance of the initial prosthetic fixation We studied CMW-1 bone cement with gentamicin in the laboratory and in a r and omized clinical study . Palacos bone cement containing gentamicin was used as the control . In the pre clinical evaluation , the CMW cement had slightly less mechanical strength . In the clinical study , 51 patients ( 51 knees ) operated on with total knee arthroplasty were studied for 2 years . We used radiostereometric analysis to measure migration of the tibial components , r and omized to fixation with either of the two types of cement . The extent and pattern of migration were similar in both groups , and we found no differences in the number , size and extent of radiolucent lines or clinical outcome . No complications occurred . Our findings suggest a need for more studies of CMW-1 bone cement containing gentamicin in a larger cohort of patients 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 Twenty-six women and three men ( 34 knees ) with osteoarthrosis were operated with the Miller-Galante I ( Zimmer , Warsaw , IN ) knee prosthesis . The patients were r and omized to either cemented or uncemented fixation of the tibial component . All patients received a TiVaAl alloy tibial plate with four pegs and titanium fiber-mesh undersurface . In the uncemented knees four screws were added . The fixation of the tibial component was determined by roentgen stereophotogrammetric analysis during the first 2 postoperative years . Rotations of the entire tibial component were recorded , as well as proximal or distal translation of various parts of the prosthetic edge corresponding to subsidence and lift-off . The uncemented components displayed almost all rotation and translation during the first 6 weeks , whereas the cemented ones displayed a more gradually increasing migration during the 2 years . Tibial component rotation about the sagittal axis was significantly increased in the uncemented knees throughout the investigation period . This corresponded to increased subsidence medially or laterally in the uncemented knees , whereas lift-off was equal in the two groups . Thin ( 8.5 mm ) uncemented tibial components displayed more subsidence than the thicker ones at the medial or lateral edge 3 months after surgery BACKGROUND A concern that arises with any change in technique is whether it affects the long-term implant stability . The objective of this study was to evaluate the early migration , measured by radiostereometric analysis ( RSA ) , and the functional outcome of the Triathlon ™ cemented knee prosthesis , operated on with or without a tourniquet . During the last decades RSA has emerged as a way to assess prosthetic fixation and long time prognosis . The method has been used extensively in both hip and knee arthroplasty . METHOD This was a single centre prospect i ve study including 60 patients r and omized into two groups operated on either with or without tourniquet .  RSA investigation was done within 2 - 3 days postoperatively after full weight bearing , and then at 3 months , 1 year and 2 years postoperatively . RESULTS There were no differences between the groups regarding the translation along or rotation around the three coordinal axes , or in maximum total point motion ( MTPM ) . At 2 years the mean MTPM ( SD ) was 0.71 mm ( 0.64 ) for the tourniquet-group and 0.53 mm ( 0.21 ) for the non-tourniquet-group . CONCLUSIONS The tibial tray of the Triathlon ™ cemented knee prosthesis showed similar early stability whether operated on with or without tourniquet . LEVEL OF EVIDENCE Level I. ARTICLE SUMMARY Article focus : A safety study for total knee replacement operated on with or without perioperative tourniquet regarding the prosthetic fixation . Strengths and limitations : Strength of this study is that it is a r and omized prospect i ve trial using an objective measuring tool . The sample size of 25 - 30 patients is reportedly sufficient for the screening of implants using RSA ( 1 - 3 ) . TRIAL REGISTRATION Clinical trials NCT01604382 , Ethics Committee approval D-nr : 144/20085 Forty uncemented total knee arthroplasties ( 36 patients ) were r and omly allocated to a Miller-Galante II prosthesis with or without hydroxyapatite/tricalcium phosphate ( HA/TCP ) coating on the titanium fiber mesh on the undersurface of the tibial component . The patients were followed for 2 years with repeated radiostereometric examinations . After 2 years , the HA/TCP tibial components displayed smaller anterior-posterior tilt and less subsidence . The mean value of maximal total point motion was small : 0.5 mm in both groups . At 24 months , there were more radiolucent lines under the tibial tray and around the stem in the uncoated group , but the clinical results did not differ . HA/TCP coating on the undersurface of the tibial component improved the stability and seemed to improve the quality of the interface between the tibial component and the bone We conducted a prospect i ve , r and omized study of 45 patients to evaluate 3 different uncemented tibial component design s in total knee arthroplasty . The stability of the components was assessed by  radiostereometry ( RSA ) , both as migration during 2 years and as inducible displacement at 2 years . The PCA resurfacing , the Tricon stem and the Tricon-M prosthesis groups showed a similar level of migration at 2 years , about 1.4 mm . In response to externally applied rotatory forces , the Tricon groups rotated more than the PCA group , interpreted as a consequence of the more conforming articular surface in the Tricon design . The series was divided into one group of continuously migrating prostheses with a poor prognosis ( unstable , one third ) and another group of prostheses in which migration stopped after 1 year ( stable , two thirds ) . With this classification , no differences between the prostheses design groups were revealed . However , the unstable group showed a larger inducible displacement by provocation , an association hitherto not established VersaBond is a newly developed bone cement . To investigate its clinical performance , VersaBond was compared to Palacos R in a prospect i ve r and omized study in total knee replacement . Fifty-nine patients ( 61 knees ) undergoing total knee replacement were r and omized to either VersaBond or Palacos R bone cement and followed for 24 months using radiostereometric analysis ( RSA ) . Up to 2 years there were no significant differences in clinical performance between the two cements . The mean/median values for implant migration were very similar for the two bone cements , as were the dispersion , and distribution of outliers . Also the proportion " stable " and " continuously migrating " implants was similar between the two cements . The result of this study indicates that VersaBond bone cement will perform at least equally as well as Palacos R in total knee replacement as regards as aseptic loosening We aim ed to determine whether not using a tourniquet in cemented TKA would affect migration of the tibial component measured by radiosterometric analysis ( RSA ) . Seventy patients were r and omized into a tourniquet group and a non-tourniquet group and using model-based RSA , the migration of the tibial component was analyzed . Primary and secondary outcome measures were maximum total point motion ( MTPM ) and translations and rotations . Follow-up period was 2 years . The tibial component was well fixated in both groups and no significant difference in migration between the two groups was detected ( P=0.632 ) . Mean MTPM ( SD ) was 0.47 mm ( 0.16 ) in the tourniquet group and 0.45 mm ( 0.21 ) in the non-tourniquet group . Absence of tourniquet indicates that stable fixation of the tibial component can be achieved in cemented TKA
target: Cemented and uncemented tibial components had different migration patterns .
  For cemented tibial components there was no difference in migration between all-poly and metal-backed components , between mobile bearing and fixed bearing , between cruciate retaining and posterior stabilized .
  Furthermore , no difference existed between TKR measured with model-based RSA or marker-based RSA methods .
  For uncemented TKR there was some variation in migration with the highest migration for uncoated TKR .
  Interpretation - The results from this meta- analysis on  RSA migration of TKR  are in line with both the survival analyses results from joint registries of these TKRs as well as revision rates results from meta-analyses , thus providing further proof for the association between early migration and late revision for loosening .
background: Purpose - We performed a systematic review and meta-analyses to evaluate the early and long-term migration patterns of  tibial components of TKR of all known RSA studies .