human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND In total knee replacement , sound early fixation of the prosthesis is crucial for achieving a good long-term result and for minimising the risk of loosening . Various types of prosthetic material , different surface textures and shapes and the incorporation of screws or pegs have been used to achieve good fixation , particularly in the uncemented knee . Hydroxyapatite ( HA ) coating of prosthetic joint components is another technique used to enhance early stability and so to improve the longevity of the prosthesis-bone fixation . HA ceramic coatings are mostly plasma sprayed onto the fixation surface of the implant . Plasma spraying is largely a ' line of sight ' technique and as such there are difficulties involved when covering three-dimensional planes , such as porous beaded fixation surfaces typically found on several knee prostheses . The objective of this study was to assess the clinical performance of the solution-deposited HA coating , Peri-Apatite , with regard to its ability to stimulate an endurable and stable implant fixation . PATIENTS AND METHODS We r and omised 60 patients into two groups ; one group received the porous coated prosthesis with solution-deposited HA  , and the other group received a prosthesis without HA . Radiostereometric examination was used as the primary tool for measuring migration in the prosthetic components . RESULTS There was a lower incidence of early subsidence in the Peri-Apatite group . At 24 months there were no differences in clinical scorings or maximal total point motion . CONCLUSION Addition of solution-deposited HA coating appears to provide better early stable fixation in a porous coated knee prosthesis 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 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 The effect of bone cement viscosity and cement mantle thickness on the migration of the Exeter  total hip prosthesis  was studied in a prospect i ve , r and omized , double-blind clinical Roentgen Stereophotogrammetric Analysis study . Forty-one cemented total hip arthroplasty in 39 patients were included and r and omized into a low/medium Simplex P cement group and a high-viscosity Simplex AF cement group . At time of stem introduction , 5 minutes after mixing , the Simplex AF was more viscous than Simplex P. No statistical difference existed between the 2 cement groups , for neither translation nor rotation migration data . Subsidence of the stem at 2-year follow-up was 1.1 + /- 0.56 mm for Simplex AF cement and 1.5 + /- 1.00 mm for Simplex P cement . The mean rotation of the acetabular components about the sagittal axis was 1.7 degrees + /- 3.8 degrees in the Simplex AF group and 0.7 degrees + /- 2.1 degrees for the Simplex P group . No effect of cement mantle thickness on migration of neither the acetabular cups nor the femoral stems was found . Although there were no differences in migration data for the cups and the stems , 2 acetabular cups in the Simplex AF group ( almost 10 % ) were revised because of mechanical loosening . Because of these findings , we suggest caution before using this new high-viscosity bone cement for fixation of acetabular components Background and purpose There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty . Theoretically , bone ingrowth into the implant should benefit from initial partial weight bearing . We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density ( BMD ) and /or the stability of the CLS stem . Patients and methods 38 patients received an uncemented CLS stem  and were  r and omized  to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months .  Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis ( RSA ) after surgery and at 3 , 12 , 24 , and 60 months . Results Periprosthetic BMD was not influenced by the type of postoperative weight bearing . BMD was reduced by 8–15 % in all Gruen zones at 3 months . Restoration toward initial BMD was observed in all zones except in zone 7 ( calcar region ) , where BMD was reduced by 22 % at 5 years . Immediate weight bearing after surgery had no influence on the stability of the CLS stem , as assessed by RSA . Interpretation Immediate full weight bearing after uncemented total hip arthroplasty is safe . There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months . BMD is reduced by more than 20 % in the calcar region around a CLS stem after 5 years 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 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 We followed prospect ively 27 patients with severe acetabular bone-stock deficiencies due to developmental dysplasia of the hip . Mean preoperative patient age was 56 ( 34–78 ) years , mean Harris hip score was 31 ( 16–66 ) points and pre-operative mean acetabular angle of Sharp was 47 ° ( 34 ° –61 ° ) . Operative acetabular reconstruction was performed in 28 hips using reinforcement ring with a hook placed in the true acetabulum and autologous bone grafting . A 2-year clinical and radiological follow-up was available in 27 hips . Mean Harris hip score improved to 91 ( 70–100 ) points . There were no clinical or radiological signs of aseptic loosening in 25 hips , and the bone graft was radiologically incorporated in all hips . In 24 hips , a radiostereometric analysis showed low rates of non-progressive translation and rotation in 21 reinforcement rings . Three rings showed progressive translation and /or rotation at the 2-year follow-up and were rated probably loose . RésuméNous avons suivi 27 malades avec des déficiences acétabulaires sévères dû à une dysplasie de développement de la hanche . L’âge moyen préopératoire des malades était de 56 ans ( 34–78 ) , le score moyen de Harris était de 31 points ( 16–66 ) et l’angle moyen de Sharp préopératoire était de 47 ° ( 34 ° –61 ° ) . La reconstruction acétabulaire a été exécutée dans 28 hanches en utilisent un anneau de renforcement avec crochet , placé dans le paléo-cotyle , avec greffe osseuse autologue . Un suivi clinique et radiologique de 2 années était disponible pour 27 hanches . Le score moyen de Harris a été amélioré à 91 points ( 70–100 ) . Il n’y avait pas de signe clinique ou radiologique de descellement aseptique dans 25 hanches et la greffe osseuse était incorporée dans toutes les hanches . Dans 24 hanches une analyse radiostéréométrique a montré un faible taux de translation et de rotation , non progressive , de 21 anneaux de renforcement . Trois anneaux ont montré une translation et/ou une rotation progressive au cours du suivi de 2 années et ont été considérés comme descellés Background In uncemented total hip arthroplasty with hydroxyapatite coating , early weight bearing is frequently practice d but there is still not much evidence to support this recommendation . Method In a prospect i ve r and omized study we evaluated the effect of partial and full weight bearing after  cementless total hip arthroplasty ( ABG ; Stryker-Howmedica ) using radiostereometric analysis ( RSA ) . Between February 1996 and February 2000 , 43 consecutive patients ( mean age 53 ( 41–63 ) years , 23 women ) with hip osteoarthrosis received an uncemented and hydroxyapatite-coated prosthesis with an anteverted stem . All patients were operated in a st and ardized way by three experienced surgeons and they were r and omized to partial ( P ) or full ( F ) weight bearing during the first 6 weeks after surgery . The patients in the partial weight bearing group were equipped with a pressuresensitive insole signaling 
    Output:
    
agent
INTERPRETATION The guidelines have improved method ological reporting in RSA studies , but adherence to these guidelines is still relatively low .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND In total knee replacement , sound early fixation of the prosthesis is crucial for achieving a good long-term result and for minimising the risk of loosening . Various types of prosthetic material , different surface textures and shapes and the incorporation of screws or pegs have been used to achieve good fixation , particularly in the uncemented knee . Hydroxyapatite ( HA ) coating of prosthetic joint components is another technique used to enhance early stability and so to improve the longevity of the prosthesis-bone fixation . HA ceramic coatings are mostly plasma sprayed onto the fixation surface of the implant . Plasma spraying is largely a ' line of sight ' technique and as such there are difficulties involved when covering three-dimensional planes , such as porous beaded fixation surfaces typically found on several knee prostheses . The objective of this study was to assess the clinical performance of the solution-deposited HA coating , Peri-Apatite , with regard to its ability to stimulate an endurable and stable implant fixation . PATIENTS AND METHODS We r and omised 60 patients into two groups ; one group received the porous coated prosthesis with solution-deposited HA  , and the other group received a prosthesis without HA . Radiostereometric examination was used as the primary tool for measuring migration in the prosthetic components . RESULTS There was a lower incidence of early subsidence in the Peri-Apatite group . At 24 months there were no differences in clinical scorings or maximal total point motion . CONCLUSION Addition of solution-deposited HA coating appears to provide better early stable fixation in a porous coated knee prosthesis 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 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 The effect of bone cement viscosity and cement mantle thickness on the migration of the Exeter  total hip prosthesis  was studied in a prospect i ve , r and omized , double-blind clinical Roentgen Stereophotogrammetric Analysis study . Forty-one cemented total hip arthroplasty in 39 patients were included and r and omized into a low/medium Simplex P cement group and a high-viscosity Simplex AF cement group . At time of stem introduction , 5 minutes after mixing , the Simplex AF was more viscous than Simplex P. No statistical difference existed between the 2 cement groups , for neither translation nor rotation migration data . Subsidence of the stem at 2-year follow-up was 1.1 + /- 0.56 mm for Simplex AF cement and 1.5 + /- 1.00 mm for Simplex P cement . The mean rotation of the acetabular components about the sagittal axis was 1.7 degrees + /- 3.8 degrees in the Simplex AF group and 0.7 degrees + /- 2.1 degrees for the Simplex P group . No effect of cement mantle thickness on migration of neither the acetabular cups nor the femoral stems was found . Although there were no differences in migration data for the cups and the stems , 2 acetabular cups in the Simplex AF group ( almost 10 % ) were revised because of mechanical loosening . Because of these findings , we suggest caution before using this new high-viscosity bone cement for fixation of acetabular components Background and purpose There is no consensus on the best rehabilitation regime after uncemented total hip arthroplasty . Theoretically , bone ingrowth into the implant should benefit from initial partial weight bearing . We investigated whether the degree of postoperative weight bearing influences the periprosthetic bone mineral density ( BMD ) and /or the stability of the CLS stem . Patients and methods 38 patients received an uncemented CLS stem  and were  r and omized  to either unrestricted postoperative weight bearing or to partial weight bearing for 3 months .  Periprosthetic BMD was measured in the 7 Gruen zones with DXA and the stability of the femoral stem was assessed by radiostereometric analysis ( RSA ) after surgery and at 3 , 12 , 24 , and 60 months . Results Periprosthetic BMD was not influenced by the type of postoperative weight bearing . BMD was reduced by 8–15 % in all Gruen zones at 3 months . Restoration toward initial BMD was observed in all zones except in zone 7 ( calcar region ) , where BMD was reduced by 22 % at 5 years . Immediate weight bearing after surgery had no influence on the stability of the CLS stem , as assessed by RSA . Interpretation Immediate full weight bearing after uncemented total hip arthroplasty is safe . There is no difference in the periprosthetic BMD or in stability of the stem as measured by RSA compared to partial weight bearing for 3 months . BMD is reduced by more than 20 % in the calcar region around a CLS stem after 5 years 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 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 We followed prospect ively 27 patients with severe acetabular bone-stock deficiencies due to developmental dysplasia of the hip . Mean preoperative patient age was 56 ( 34–78 ) years , mean Harris hip score was 31 ( 16–66 ) points and pre-operative mean acetabular angle of Sharp was 47 ° ( 34 ° –61 ° ) . Operative acetabular reconstruction was performed in 28 hips using reinforcement ring with a hook placed in the true acetabulum and autologous bone grafting . A 2-year clinical and radiological follow-up was available in 27 hips . Mean Harris hip score improved to 91 ( 70–100 ) points . There were no clinical or radiological signs of aseptic loosening in 25 hips , and the bone graft was radiologically incorporated in all hips . In 24 hips , a radiostereometric analysis showed low rates of non-progressive translation and rotation in 21 reinforcement rings . Three rings showed progressive translation and /or rotation at the 2-year follow-up and were rated probably loose . RésuméNous avons suivi 27 malades avec des déficiences acétabulaires sévères dû à une dysplasie de développement de la hanche . L’âge moyen préopératoire des malades était de 56 ans ( 34–78 ) , le score moyen de Harris était de 31 points ( 16–66 ) et l’angle moyen de Sharp préopératoire était de 47 ° ( 34 ° –61 ° ) . La reconstruction acétabulaire a été exécutée dans 28 hanches en utilisent un anneau de renforcement avec crochet , placé dans le paléo-cotyle , avec greffe osseuse autologue . Un suivi clinique et radiologique de 2 années était disponible pour 27 hanches . Le score moyen de Harris a été amélioré à 91 points ( 70–100 ) . Il n’y avait pas de signe clinique ou radiologique de descellement aseptique dans 25 hanches et la greffe osseuse était incorporée dans toutes les hanches . Dans 24 hanches une analyse radiostéréométrique a montré un faible taux de translation et de rotation , non progressive , de 21 anneaux de renforcement . Trois anneaux ont montré une translation et/ou une rotation progressive au cours du suivi de 2 années et ont été considérés comme descellés Background In uncemented total hip arthroplasty with hydroxyapatite coating , early weight bearing is frequently practice d but there is still not much evidence to support this recommendation . Method In a prospect i ve r and omized study we evaluated the effect of partial and full weight bearing after  cementless total hip arthroplasty ( ABG ; Stryker-Howmedica ) using radiostereometric analysis ( RSA ) . Between February 1996 and February 2000 , 43 consecutive patients ( mean age 53 ( 41–63 ) years , 23 women ) with hip osteoarthrosis received an uncemented and hydroxyapatite-coated prosthesis with an anteverted stem . All patients were operated in a st and ardized way by three experienced surgeons and they were r and omized to partial ( P ) or full ( F ) weight bearing during the first 6 weeks after surgery . The patients in the partial weight bearing group were equipped with a pressuresensitive insole signaling 
    Output:
    