The beneficial effect of hydroxyapatite lasts Preoperative gait patterns and BMI are associated with tibial component migration Cemented tibial component fixation performs better than cementless fixation Effect of bioactive coating of the tibial component on migration pattern in uncemented total knee arthroplasty: a randomized RSA study of 14 knees presented according to new RSA-guidelines Celecoxib does not appear to affect prosthesis fixation in total knee replacement Good diagnostic performance of early migration as a predictor of late aseptic loosening of acetabular cups: results from ten years of follow-up with Roentgen stereophotogrammetric analysis (RSA). Denosumab reduces early migration in total knee replacement Migration of a cemented fixed-bearing, polished titanium tibial baseplate (Genesis II) at ten years : a radiostereometric analysis. Early Migration of the Tibial Component of the Buechel-Pappas Total Ankle Prosthesis Early migration characteristics of a hydroxyapatite-coated femoral stem: an RSA study Absence of a Tourniquet Does Not Affect Fixation of Cemented TKA: A Randomized RSA Study of 70 Patients. Kinematics and early migration in single-radius mobile- and fixed-bearing total knee prostheses. Similar early migration when comparing CR and PS in Triathlon™ TKA: A prospective randomised RSA trial. Tibial component fixation in porous- and hydroxyapatite-coated total knee arthroplasty: a radiostereo metric evaluation of migration and inducible displacement after 5 years. The effect of Palamed® G bone cement on early migration of tibial components in total knee arthroplasty Hydroxyapatite augmentation of the porous coating improves fixation of tibial components. A randomised RSA study in 116 patients. Cemented versus uncemented fixation of the femoral component of the NexGen CR total knee replacement in patients younger than 60 years: a prospective randomised controlled RSA study. Knee joint loading and tibial component loosening. RSA and gait analysis in 45 osteoarthritic patients before and after TKA. Comparison of cementing techniques of the tibial component in total knee replacement 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. Mobile vs. fixed meniscal bearing in total knee replacement: a randomised radiostereometric study. The stability of three different cementless tibial components. A randomized radiostereometric study in 45 knee arthroplasty patients. Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations Evaluation of micromotion in cemented vs uncemented knee arthroplasty in osteoarthrosis and rheumatoid arthritis. Randomized study using roentgen stereophotogrammetric analysis. 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.
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 and purpose There is no st and ard for patient triage in  total knee arthroplasty ( TKA ) based on joint functional characteristics . This is largely due to the lack of objective postoperative measurement of success in TKA in terms of function and longevity , and the lack of knowledge of preoperative metrics that influence outcome . We examined the association between the preoperative mechanical environment of the patients knee joint during gait and the post-TKA stability of the tibial component  as measured with  radiostereometric analysis ( RSA ) .  Methods 37 subjects were recruited out of a larger r and omized RSA trial .  3-dimensional gait analysis was performed in the preoperative week . Longitudinal RSA data were gathered postoperatively at 6 months and 1 year . Results We found a statistically significant association between the pattern of the knee adduction moment during gait preoperatively and the total migration of the implant at 6 months postoperatively . A substantial proportion of the variability in the total postoperative tibial component migration ( R2 = 0.45 ) was explained by a combination of implant type , preoperative knee joint loading patterns during gait , and body mass index at 6 months postoperatively . The relationships did not remain statistically significant at 1 year postoperatively . Interpretation Our findings support the hypothesis that preoperative functional characteristics of patients , and particularly joint loading patterns during activities of daily living , are important for outcome in TKA . This represents a first step in the development of predictive models of objective TKA outcome based on preoperative patient characteristics , which may lead to better treatment strategies . Clinical Trials.gov ( NCT00405379 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 Bioactive coating of uncemented  total knee arthroplasty ( TKA ) is believed to increase bone ingrowth and enhance early fixation of the TKA . In a prospect i ve r and omized study using radiostereometric analysis ( RSA ) we examined migrations of the tibial implant , in an uncemented TKA with and without bioactive coating . The study was performed according to new RSA guidelines , and focus was put on some important method ological issues . Material s and methods Twenty-three patients with osteoarthrosis of the knee received an uncemented Duracon TKA either with bioactive ( hydroxyapatite or periapatite ) coating ( + HA ) or without bioactive coating ( −HA ) . Patients had RSA examinations postoperatively and at 3 , 6 and 12 months . Nine patients were excluded during the study result ing in 14 knees for final analysis . Results At 12 months follow-up we found no significant differences in migrations between the two groups . However , in general the −HA group migrated more than the + HA group , and we found a significant larger variation in migration pattern in the −HA group . In the + HA group the tibia component stabilized after 6 months , whereas the −HA group showed continuous migration . Subsidence and posterior tilt were the main migration patterns in both groups . Conclusions Bioactive coating of TKA seems to enhance early stabilization of the tibia component . Similar results are found in previous studies 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 Excessive early migration of femoral stems following total hip arthroplasty and tibial components following total knee arthroplasty is associated with their long-term survival and allows reliable early evaluation of implant performance . However , a similar relationship involving acetabular components following hip arthroplasty has not been evaluated . This prospect i ve , long-term study with clinical and Roentgen stereophotogrammetric analysis ( RSA ) follow-up establishes the existence of this relationship and its associated diagnostic performance . METHODS Thirty-nine consecutive patients ( forty-one hips ) who underwent total hip arthroplasty with a cemented Exeter stem and a cemented Exeter all-polyethylene cup had prospect i ve clinical and RSA follow-up . Patients were evaluated postoperatively at six weeks , at three , six , and twelve months , and annually thereafter . Conventional anteroposterior and lateral radiographs were made at six weeks and at two , five , and ten years postoperatively as well as when indicated . The mean duration of follow-up ( and st and ard deviation ) was 9.4 ± 3.2 years . No patients were lost to follow-up ; fifteen patients died during the follow-up period . RESULTS Eleven acetabular components were observed to be loose on conventional radiographs after a mean of seventy-six months ( range , twelve to 140 months ) . During the first two postoperative years , the failed acetabular components showed markedly greater and more rapid cranial translation and sagittal rotation . Both cranial translation ( hazard ratio = 19.9 [ 95 % confidence interval , 4.94 to 80.0 ] , p < 0.001 ) and sagittal rotation ( hazard ratio = 11.1 [ 95 % confidence interval , 2.83 to 43.9 ] , p = 0.001 ) were strong risk factors for late aseptic loosening . Eight of the eleven failed components showed a distinctive pattern of excessive cranial translation combined with excessive sagittal rotation . The associated diagnostic performance of two-year cranial translation and /or sagittal rotation for predicting late aseptic loosening of the acetabular component was good ( area under the receiver operating characteristic curve , 0.88 [ 95 % confidence interval , 0.74 to 1.00 ; p < 0.001 ] and 0.84 [ 95 % confidence interval , 0.68 to 1.00 ; p = 0.001 ] , respectively ) . CONCLUSIONS Early migration , as measured by RSA at two years postoperatively , has good diagnostic capabilities for the detection of acetabular components at risk for future aseptic loosening , and this method appears to be an appropriate means of assessing the performance of new implants or implant-related changes Background and purpose — Aseptic loosening is a main cause of late revision in total knee replacement ( TKR ) . Migration of implants as measured by radiostereometric analysis ( RSA ) can predict future loosening . This migration is associated with bone resorption . Denosumab is a human monoclonal antibody that binds to receptors on osteoclast precursors and osteoclasts . This prevents osteoclast formation , result ing in less bone resorption in cortical and trabecular bone . We investigated whether denosumab can reduce migration of TKR , as measured with RSA . Patients and methods — In this 2-center , r and omized , double-blind  placebo-controlled  trial , 50 patients with osteoarthritis of the knee were treated with an injection of either denosumab ( 60 mg ) or placebo 1 day after knee replacement surgery and again after 6 months . RSA was performed postoperatively and after 6 , 12 , and 24 months . The primary effect variable was RSA maximal total point motion ( MTPM ) after 12 months . We also measured other RSA variables and the knee osteoarthritis outcome score ( KOOS ) . Results — The primary effect variable , MTPM after 12 months , showed that migration in the denosumab group was statistically significantly less than in the controls . Denosumab  MTPM 12 months was reduced by one-third ( denosumab : median 0.24 mm , 10 % and 90 % percentiles : 0.15 and 0.41 ; placebo : median 0.36 mm , 10 % and 90 % percentiles : 0.20 and 0.62 ) . The secondary MTPM variables ( 6 and 24 months ) also showed a statistically significant reduction in migration . There was no significant difference in MTPM for the period 12–24 months . KOOS sub-variables were similiar between denosumab and placebo after 12 and 24 months . Interpretation — Denosumab reduces early migration in total knee replacement , as in previous trials using bisphosphonates . As migration is related to the risk of late loosening , denosumab may be beneficial for long-term results 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 Interest in mobile-bearing total ankle arthroplasty has increased in recent years . Clinical studies show favorable but varying results , with survival rates between 70 % and 90 % at 10-year followup . Design -specific differences in early migration patterns might explain variations in the results and modes of failure . Using radiostereometric analysis ( RSA ) we prospect ively followed 15 RA patients with a cementless mobile-bearing total ankle arthroplasty .  The American Orthopaedic Foot and Ankle Society ankle score and radiostereometric radiographs  were evaluated immediately postoperatively , 6 weeks postoperatively , 3 months , 6 months , and 12 months postoperatively and yearly thereafter . The postoperative clinical results improved . We observed increased migration of the tibial component during the first 3 months , but this stabilized by the 6 month followup . The mean lateral-medial migration was 0.8 mm , distal-proximal migration was 0.9 mm , and posteroanterior migration was −0.5 mm . The latter implies the total result ant migration was in anterior and valgus tilting of this tibial component . However , migration stabilized at 6 months postoperatively . We believe the surgical technique ( anterior cortical window for placement ) and the method of tibial fixation likely explain this migration . Level of Evidence : Therapeutic , Level IV . See Guidelines for Authors for a complete description of levels of evidence Measurement of early stem subsidence can be used to predict the likelihood of long-term femoral component loosening and clinical failure . Data that examines the early migration pattern of clinical ly proven stems will provide clinicians with useful baseline data with which to compare new stem design s. This study was performed to evaluate the early migration pattern of a hydroxyapatite-coated press-fit femoral component that has been in use for over ten years . We enrolled 30 patients who underwent THA for osteoarthritis . The median age was 70 years ( range , 55–80 years ) . Patients were clinical ly assessed using the Harris hip score .  Radiostereometric analysis was used to evaluate stem migration at three to four days , six months , one year and two years . We observed a mean subsidence of 0.73 mm at six months , 0.62 mm at one year and 0.58 mm at two years and a mean retroversion of 1.82 ° at six months , 1.90 ° at one year and 1.59 ° at two years . This data suggests that subsidence is confined to the first six months after which there was no further subsidence . The results from this study can be compared with those from novel cementless stem design s to help predict the long-term outcome one may expect from new cementless stem design 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 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 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 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 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 In a single-blind , r and omised series of knee replacements in 116 patients , we used radiostereometric analysis ( RSA ) to measure micromotion in three types of tibial implant fixation for two years after knee replacement . We compared hydroxyapatite-augmented porous coating , porous coating , and cemented fixation of the same design of tibial component . At one to two years , porous-coated implants  migrated at a statistically significantly higher rate than hydroxyapatite-augmented or cemented implants . There was no significant difference between hydroxyapatite-coated and cemented implants . We conclude that hydroxyapatite augmentation may offer a clinical ly relevant advantage over a simple porous coating for tibial component fixation , but is no better than cemented fixation The optimal mode of femoral fixation in total knee arthroplasty ( TKA ) remains controversial , especially for the young patient . In a prospect i ve r and omised study we compared the magnitude and pattern of the fixation of cemented versus uncemented femoral components during 2 years in patients younger than 60 years . Forty-one knees in 41 patients were r and omised to receive a NexGen ( Zimmer , Warsaw , USA  ) cruciate-retaining TKA with either a cemented or an uncemented non HA-coated femoral component . The patients were examined by radiostereometric analysis ( RSA ) , as well as clinical and radiological evaluation . The magnitude and pattern of migration as measured by RSA did not differ significantly between the cemented and uncemented fixation during the 2-year follow-up , nor were there any differences between the groups in clinical parameters . These findings suggest that an uncemented and non HA-coated femoral component may behave equally as well as a cemented one in the long-term We report a prospect i ve study of gait and tibial component migration  in 45 patients with osteoarthritis treated by total knee arthroplasty ( TKA ) .  Migration  was measured over two years using roentgen stereophotogrammetry . We used the previously established threshold of 200 microm migration in the second postoperative year to distinguish two groups : a risk group of 15 patients and a stable group of 28 patients . We performed  gait analysis before operation and at six months and at two years after TKA . On all three occasions we found significant differences between the two groups in the mean sagittal plane moments of the knee joint . The risk group walked with higher peak flexion moments than the stable group . The two groups were not discriminated by any clinical or radiological criteria or other gait characteristics . The relationship which we have found between gait with increased flexion moments and risk of tibial component loosening warrants further study as regards the aetiology of prosthetic loosening and possible methods of influencing its incidence A few studies have shown that cementing the stem enhances fixation of the tibial baseplate in total knee replacement ( TKR ) . Even the horizontal technique has been shown to provide good fixation . We used radiostereometry to study migration of the tibial component in 30 knees operated with Profix TKR . The knees were r and omised for either complete ( both under the baseplate and around the stem ) or horizontal ( only under the baseplate ) cementing of the tibial component . At two years the tibial baseplate rotated externally a median of 0.18 ° in the uncemented stem group and internally a median of 0.23 ° in the cemented stem group . The tibial baseplate subsided 0.14 mm in the cemented stem group , and no translation was seen in the uncemented stem group . The differences in migration were small and probably without clinical significance . The findings do not favour either of the cementing techniques in TKR.RésuméPeu d’études ont démontré que la fixation cimentée de la queue améliorait la fixation du plateau tibial dans les prothèses totales du genou . Par ailleurs , les fixations horizontales ont également montré une bonne fixation . Nous avons utilisé la radiostéréométrie pour étudier la migration du composant tibial dans 30 genoux de type Profix . Les genoux ont été r and omisés cimentation sous le plateau et autour de la queue ou cimentation horizontale uniquement sous le plateau . À 2 ans le plateau tibial présente une rotation externe de 0,18 ° dans les PTG avec une queue non cimentée et une rotation interne moyenne de 0,23 ° dans le groupe des queues cimentées . La base du plateau tibial s’enfonce de 0,14 mm dans le groupe des queues cimentées et il n’y a pas de translation dans le groupe des queues non cimentées . En conclusion , la différence au niveau de la migration est minime et sans signification clinique . Cette étude ne permet pas de choisir dans les prothèses totales du genou l’une des deux techniques de cimentation 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 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 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 Background Clinical consequences of alignment errors in  total knee replacement ( TKR ) have led to the rigorous evaluation of surgical alignment techniques . Rotational alignment in the transverse plane has proven particularly problematic , with errors due to component malalignment relative to bone anatomic l and marks and an overall mismatch between the femoral and tibial components ’ relative positions . Ranges of nominal rotational alignment are not well defined , especially for the tibial component and for relative rotational mismatch , and some studies advocate the use of mobile-bearing TKR to accommo date the result ing small rotation errors . However , the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood . This prospect i ve , in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR . Methods Eighty patients were implanted with mobile-bearing TKR .  Rotational alignment of the femoral and tibial components was measured from postoperative CT scans . All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic l and marks and relative rotational mismatch between the femoral and tibial components . Axial rotation motion of the femoral , tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion . Results Axial rotation motion was generally accomplished in two phases , dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion . Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80 ° . Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to internal rotation during mid-flexion . Knees with femoral-tibial rotational mismatch had significantly lower total axial rotation compared to knees with nominal alignment . Conclusions Maintaining relative rotational mismatch within ±5 ° during TKR provided for controlled knee axial rotation during flexion . TKR with rotational alignment outside of defined surgical norms , with either positive or negative mismatch , experienced measurable kinematic differences and presented different patterns of axial rotation motions during passive knee flexion compared to TKR with nominal mismatch . These findings support previous studies linking prosthesis rotational alignment with inferior clinical and functional outcomes .Trial Registration Clinical Trials Twenty-four patients ( 25 knees ) with osteoarthrosis ( OA ) and 19 patients ( 20 knees ) with rheumatoid arthritis ( RA ) were operated with bi-tricompartmental knee arthroplasty .  The patients were r and omized to cemented or cementless fixation of the tibial component . The fixation of the tibial components was examined with roentgen stereophotogrammetric analysis ( RSA ) up to 24 months after operation . The following parameters representing tibial component micromotion were measured : ( 1 ) maximum migration of the prosthetic edge ( maximum total point motion , MTPM ) ; ( 2 ) distal migration of the prosthetic center ( subsidence ) ; ( 3 ) maximum proximal movements of the prosthetic edge ( " lift-off " ) ; and ( 4 ) prosthetic rotations , corresponding to internal/external rotation , adduction/abduction , and forward/backward tilt of the tibial component . All prostheses displayed significant micromotions , which tended to decrease 3 - 6 months after the operation . The average migration after 2 years , when measured as maximum single axis rotation , and MTPM were about 0.9 degrees-1.5 degrees and 1.0 - 1.5 mm , respectively , in all four groups . There were no statistically significant differences between cemented and cementless prostheses in either the OA or the RA group . The fixation in the RA patients did not significantly differ from that of the OA patients , perhaps because the RA patients had lower weight and were living a more sedentary life 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
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 .
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 .