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 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 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 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 Prosthesis migration in bone inevitably occurs in cemented and uncemented total knee arthroplasty tibial components . Cemented design s as the gold st and ard give immediate fixation whereas cementless design s need a period of bone ingrowth onto the surface irregularities of the implants . The addition of bioactive coatings may enhance this process of ingrowth . A controlled r and omized prospect i ve RSA study was carried out on 26 Duracon implants in a rheumatoid arthritis patient group to evaluate the effect of a periapatite coating on the fixation of the tibial tray . The coated and the noncoated groups were matched for sex , age , body mass index , and HSS Knee Score . Stage of preoperative joint destruction and preoperative and postoperative mechanical leg axis showed no differences . We saw no differences in migration between the two groups , but a trend for lesser translations along and rotations about all three axes in the periapatite group . The periapatite-coated components showed a lower variance in subsidence than did the uncoated components . Both groups also showed a high variance in anterior tilting of the components . The cementless PA-coated Duracon prosthesis used in patients with RA may provide improved fixation of tibial components although we could not demonstrate improvement in this small controlled series . Level of Evidence : Therapeutic Level II . See the Guidelines for Authors for a complete description of levels of evidence Surgery and other invasive therapies are complex interventions , the assessment of which is challenged by factors that depend on operator , team , and setting , such as learning curves , quality variations , and perception of equipoise . We propose recommendations for the assessment of surgery based on a five-stage description of the surgical development process . We also encourage the widespread use of prospect i ve data bases and registries . Reports of new techniques should be registered as a professional duty , anonymously if necessary when outcomes are adverse . Case series studies should be replaced by prospect i ve development studies for early technical modifications and by prospect i ve research data bases for later pre-trial evaluation . Protocol s for these studies should be registered publicly . Statistical process control techniques can be useful in both early and late assessment . R and omised trials should be used whenever possible to investigate efficacy , but adequate pre-trial data are essential to allow power calculations , clarify the definition and indications of the intervention , and develop quality measures . Difficulties in doing r and omised clinical trials should be addressed by measures to evaluate learning curves and alleviate equipoise problems . Alternative prospect i ve design s , such as interrupted time series studies , should be used when r and omised trials are not feasible . Established procedures should be monitored with prospect i ve data bases to analyse outcome variations and to identify late and rare events . Achievement of improved design , conduct , and reporting of surgical research will need concerted action by editors , funders of health care and research , regulatory bodies , and professional societies Fixation of the tibial component in total knee arthroplasty in younger patients remains controversial . We evaluate the results of three different types of fixation of the Profix total knee arthroplasty  in a r and omized controlled trial of 97 consecutive knees ( 85 patients ) with osteoarthrosis or inflammatory arthritis with 2-year followup of all patients . We r and omized patients to three different types of fixation of the tibial component : cemented , uncemented ( HA coated ) with screws , or uncemented ( HA coated ) without screws . We performed clinical evaluations and radiostereometric analysis at 6 weeks , and 3 , 6 , 12 and 24 months postoperatively . The knees in the uncemented groups migrated more than those in the cemented group during the first 3 months , but at 2 years we observed no differences . The uncemented implants  displayed all migration within the first 3 months . The cemented implants did not stabilize but had continuously increasing migration during the followup . Cementless implants without screws  did not migrate more than implants with screws and displayed similar pattern of migration , indicating screws do not improve fixation .  Uncemented fixation using hydroxyapatite-coated implants without screws seems to be the best solution for the younger patient . Level of Evidence : Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence 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 We report prospect i ve clinical and radiographic outcomes of a series of 219 hydroxyapatite-coated Duracon ( Stryker Howmedica Osteonics Corporation , Kalamazoo , Mich ) total knee arthroplasties with a follow-up of 5 to 8 years .  Knee Society Score , Western Ontario and McMaster Universities Osteoarthritis index ( WOMAC ) , and SF-12 Health Status Question naire were used . Analysis of fluoroscopic radiographs was performed with the American Knee Society Score .  All living patients ( 186 knees ) were followed up . Twenty-eight patients ( 30 knees ) had died . The preoperative 
    Output:
    
agent
INTERPRETATION There was a clinical ly relevant association between early migration of TKPs and late revision for loosening .
***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 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 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 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 Prosthesis migration in bone inevitably occurs in cemented and uncemented total knee arthroplasty tibial components . Cemented design s as the gold st and ard give immediate fixation whereas cementless design s need a period of bone ingrowth onto the surface irregularities of the implants . The addition of bioactive coatings may enhance this process of ingrowth . A controlled r and omized prospect i ve RSA study was carried out on 26 Duracon implants in a rheumatoid arthritis patient group to evaluate the effect of a periapatite coating on the fixation of the tibial tray . The coated and the noncoated groups were matched for sex , age , body mass index , and HSS Knee Score . Stage of preoperative joint destruction and preoperative and postoperative mechanical leg axis showed no differences . We saw no differences in migration between the two groups , but a trend for lesser translations along and rotations about all three axes in the periapatite group . The periapatite-coated components showed a lower variance in subsidence than did the uncoated components . Both groups also showed a high variance in anterior tilting of the components . The cementless PA-coated Duracon prosthesis used in patients with RA may provide improved fixation of tibial components although we could not demonstrate improvement in this small controlled series . Level of Evidence : Therapeutic Level II . See the Guidelines for Authors for a complete description of levels of evidence Surgery and other invasive therapies are complex interventions , the assessment of which is challenged by factors that depend on operator , team , and setting , such as learning curves , quality variations , and perception of equipoise . We propose recommendations for the assessment of surgery based on a five-stage description of the surgical development process . We also encourage the widespread use of prospect i ve data bases and registries . Reports of new techniques should be registered as a professional duty , anonymously if necessary when outcomes are adverse . Case series studies should be replaced by prospect i ve development studies for early technical modifications and by prospect i ve research data bases for later pre-trial evaluation . Protocol s for these studies should be registered publicly . Statistical process control techniques can be useful in both early and late assessment . R and omised trials should be used whenever possible to investigate efficacy , but adequate pre-trial data are essential to allow power calculations , clarify the definition and indications of the intervention , and develop quality measures . Difficulties in doing r and omised clinical trials should be addressed by measures to evaluate learning curves and alleviate equipoise problems . Alternative prospect i ve design s , such as interrupted time series studies , should be used when r and omised trials are not feasible . Established procedures should be monitored with prospect i ve data bases to analyse outcome variations and to identify late and rare events . Achievement of improved design , conduct , and reporting of surgical research will need concerted action by editors , funders of health care and research , regulatory bodies , and professional societies Fixation of the tibial component in total knee arthroplasty in younger patients remains controversial . We evaluate the results of three different types of fixation of the Profix total knee arthroplasty  in a r and omized controlled trial of 97 consecutive knees ( 85 patients ) with osteoarthrosis or inflammatory arthritis with 2-year followup of all patients . We r and omized patients to three different types of fixation of the tibial component : cemented , uncemented ( HA coated ) with screws , or uncemented ( HA coated ) without screws . We performed clinical evaluations and radiostereometric analysis at 6 weeks , and 3 , 6 , 12 and 24 months postoperatively . The knees in the uncemented groups migrated more than those in the cemented group during the first 3 months , but at 2 years we observed no differences . The uncemented implants  displayed all migration within the first 3 months . The cemented implants did not stabilize but had continuously increasing migration during the followup . Cementless implants without screws  did not migrate more than implants with screws and displayed similar pattern of migration , indicating screws do not improve fixation .  Uncemented fixation using hydroxyapatite-coated implants without screws seems to be the best solution for the younger patient . Level of Evidence : Therapeutic Level I. See the Guidelines for Authors for a complete description of levels of evidence 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 We report prospect i ve clinical and radiographic outcomes of a series of 219 hydroxyapatite-coated Duracon ( Stryker Howmedica Osteonics Corporation , Kalamazoo , Mich ) total knee arthroplasties with a follow-up of 5 to 8 years .  Knee Society Score , Western Ontario and McMaster Universities Osteoarthritis index ( WOMAC ) , and SF-12 Health Status Question naire were used . Analysis of fluoroscopic radiographs was performed with the American Knee Society Score .  All living patients ( 186 knees ) were followed up . Twenty-eight patients ( 30 knees ) had died . The preoperative 
    Output:
    