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: Two surgical strategies are possible in total knee arthroplasty ( TKA ) : a measured resection technique , in which bone l and marks are used to guide resections equal to the distal and posterior thickness of the femoral component , or a gap-balancing approach , in which equal collateral ligament tension in flexion and extension is sought before and as a guide to final bone cuts . In this study performed with computer assisted system , we compared the 2 different methods in 126 patients followed prospect ively in order to analyze the effect of both the techniques on joint-line ( JL ) maintenance , axial limb restoration and components position . The gap technique showed a statistical increase in the post-operative value when compared with the measured resection technique , ( P = 0.008 ) . When comparing the two groups regarding to the pre-operative deformity , we have found a statistical difference ( P = 0.001 ) in case of moderate pre-operative deformity ( less than 10 ° ) , and the measured resection technique showed a slight superiority in preserving a joint line more faithful to the pre-operative . We found an ideal alignment for the mechanical axis ( 180 ° ± 3 ° ) ( 95 % of cases ) . In six cases ( 5 % ) , the mean post-operative value exceeded ( varus or valgus ) the ideal value by more than 3 ° . In the frontal plane , a good alignment was observed for both femoral and tibial components without a significant difference between the two techniques . In the sagittal plane was found more alignment variability due to the different implants used and their ideal starting slope , from 7 ° to 3 ° . Finally , the surgeon can use the approach with which he has more confidence ; however , as the measured resection technique causes less reduction in the post-operative joint-line position , in case of shortening of patellar tendon or patella infera , this technique is preferable A total knee arthroplasty can be completed using two techniques ; measured resection or gap balancing . A prospect i ve blinded r and omized controlled trial was completed with 103 patients r and omized to measured resection ( n = 52 ) or gap balancing ( n = 51 ) . Primary outcome measure was femoral component rotation . Secondary outcome measures were joint-line change , gap symmetry and function and quality -of-life outcomes .  Gap balancing result ed in a significantly raised joint-line compared to measured resection .  Gap symmetry was significantly better using gap balancing .  Functional outcomes and quality -of-life were not significantly different at 24 months . Using computer navigation , gap balancing significantly raises the joint-line in order to improve gap symmetry . This does not result in a clinical difference in function or quality of life at 24 months Purpose The optimal coronal alignment is still under debate . However , in most of the studies , alignment was only assessed using radiographs , which are not accurate enough for assessment of tibial and femoral TKA position . The primary purpose of this study was to assess the relationship between coronal TKA alignment using 3D-reconstructed CTs and clinical outcome in patients with preoperative varus in comparison with patients with natural or valgus deformity . It was the hypothesis that neutral limb alignment shows a better outcome after TKA . Methods Prospect ively collected data of 38 patients were included . The clinical and radiological follow-up was 24 months . The patients were grouped into two groups with regard to their preoperative limb alignment . Group A ( varus ) consisted of 21 patients with preoperative varus of 3 ° or more , while group B ( non-varus ) consisted of 17 patients with  neutral  ( − 3 < 0 > + 3 ) or valgus alignment ( > + 3 ) . For assessment of TKA component position and orientation , 3D-reconstructed CT was used . The measurements of the deviation from the whole limb mechanical axis ( HKA angle ) and the joint line alignment in the femoral ( mLDFA ) and the tibial side ( MPTA ) were assessed in the preoperative leg as well as during follow-up after TKA . For clinical outcome assessment , the Knee Society Score ( KSS ) was used at 1 and 2 years postoperatively . Correlation between KSS score and each variable was done using a linear and quadratic regression model ( p < 0.05 ) . Results The mean postoperative HKA angle was − 1.3 ( varus ) in the varus group and + 1.4 ( valgus ) in the non-varus group . Overall , significant correlations between the preoperative and postoperative alignments were found . In the preoperatively non-varus group , a highly significant correlation was found between neutral limb alignment ( HKA = 0 ° ± 3 ° ) and higher KSS ( r2 = 0.74 , p = 0.00 ) . In the varus group , no correlation was found between the postoperative whole limb alignment and the components ’ position in the coronal plane to KSS score . Conclusion A significant correlation was found between neutral limb alignment and higher KSS only in patients with preoperative non-varus alignment . The concept of constitutional varus alignment is still under debate . Moreover , it appears that one should aim for a more individualized , alignment target based on the individual knee morphotype . Level of evidence Diagnostic study , Level II Background Femoral component rotation ( FCR ) is one of the most important factors in total knee arthroplasty . In this prospect i ve study , we used three different techniques for FCR and analyzed their accuracy with postoperative axial computed tomography ( CT ) images . We also evaluated effect of FCR to clinical outcome . Methods One hundred sixty-five patients were r and omly allocated into three groups . In the measured resection group , FCR was set by externally rotating the axis 3 ° off the posterior femoral condylar axis . In the tensor group , a gap-tensioning device set at 20 lbf was used . In the block group , spacer blocks of various thicknesses were used . The FCR angle ( FCRa ) was measured on postoperative axial CT as an angle between the clinical transepicondylar and posterior condylar axes of the femoral component . Outliers were defined as FCRas deviated more than 3 ° either internally or externally . Postoperative 2 year clinical scores and knee range of motion were checked . Results The tensor group had significantly better positioning of the femoral component to the neutral position compared with the measured resection group and the block group ( mean FCRa : internal rotation 1.79 , 0.43 and 2.63 ° , respectively , p < 0.001 ) . The outliers were also least frequent in the tensor group ( 35 , 16 and 40 % , respectively , p = 0.02 ) . There were no significant differences in postoperative 2 year clinical results among groups . Conclusions Gap technique with a 20-lbf tensor device was the most accurate and precise method for obtaining adequate FCR . Measured resection with 3 ° external rotation and gap technique with blocks could lead to internal rotation of the femoral component . Postoperative 2 year clinical results were not significantly different among groups with different techniques for FCR.Trial registration The study was registered in the Clinical Research information Service ( trial number : KCT0000129 ) in Korea . Registration date is 23rd of June , 2011 Purpose As patellar tracking and loading is influenced by tibial tuberosity and trochlear groove ( TT – TG ) distance , patellar height , thickness and tilt as well as TKA component position , it was our hypothesis that these parameters significantly correlate with patellar BTU intensity and localization in SPECT/CT . The purpose of the study was to investigate whether TKA component position as well as the height , thickness and tilt of the unresurfaced patella influences the intensity and the distribution pattern of BTU in SPECT/CT . Methods A total of 62 consecutive patients who underwent primary TKA without patellar resurfacing were prospect ively included . Demographic data such as age , gender , side and type of primary TKA were noted . All patients underwent clinical and radiological examination  in a specialized knee clinic , including st and ardized radiographs ( anterior – posterior and lateral weight bearing , patellar skyline view ) and Tc-99m-HDP-SPECT/CT before , 12 and 24 months after TKA . SPECT/CT images were analysed on 3D reconstructed images . Rotational , sagittal and coronal position of the tibial and femoral TKA components was assessed using a previously vali date d analysis software . Measurements of BTU including intensity and anatomical distribution pattern were also performed from 3D data . The patellar height , thickness and tilt were measured , and the distance between TT and TG was measured using axial CT images . Univariate analysis was performed to identify any correlations between BTU and TKA component position and patellar measurements ( p < 0.05 ) . Results The highest median BTU was measured in the superior posterior parts of the patella . A statistically significant correlation was found between valgus alignment of the femoral TKA and increased BTU at the lateral patellar regions ( p < 0.05 ) . External rotation of the tibial TKA correlated with increased BTU at the lateral superior joint adjacent part ( p < 0.05 ) . No correlation was found between the tibial TKA  position ( varus – valgus , anterior and posterior slope ) , TT – TG distance , patellar height and patellar BTU values . Conclusions A significant correlation of increased patellar BTU was found with femoral valgus TKA alignment . These findings highlight the importance of femoral TKA position in coronal plane with regard to post-operative patellar tracking . Moreover , these facts might explain anterior knee pain in unhappy TKA with femoral valgus alignment . Level of evidence Diagnostic study , Level II BACKGROUND For establishing femoral component position , gap-balancing ( GB ) and measured resection ( MR ) techniques were compared using a force sensor . METHODS Ninety-one patients were r and omized to undergo primary total knee arthroplasty using either MR ( n = 43 ) or GB ( n = 48 ) technique using a single total knee arthroplasty design .  GB was performed with an instrumented tensioner . Force sensor data were obtained before the final implantation . RESULTS GB result ed in greater range of femoral component rotation vs MR ( 1.5 ° ± 2.9 ° vs 3.1 ° ± 0.5 ° , P < .05 ) and posterior condylar cut thickness medially ( 10.2 ± 2.0 mm vs 9.0 ± 1.3 mm ) and laterally ( 8.5 ± 1.9 mm vs 6.4 ± 1.0 mm ) . Force sensor data showed a decreased intercompartmental force difference at full flexion in GB ( .8 ± 2.3 vs 2.0 ± 3.3u , 1u ≈ 15 N , P < .05 ) . CONCLUSION GB result ed in a greater range of femoral component rotation and thicker posterior condylar cuts result ing in an increased flexion space relative to MR . Intercompartmental force difference trended toward a more uniform distribution between full extension and full flexion in the GB vs MR group While patient-specific instrumentation ( PSI ) in total knee arthroplasty ( TKA ) allows for transfer of the preoperative plan onto bony l and marks , the soft tissue balancing is not affected . The goals of this r and omized clinical trial were to compare PSI and the measured resection technique ( conventional ) with PSI and the gap balancing technique .  Fifty patients were r and omized to TKA with conventional PSI ( PSI-S ) ( n = 25 ) or to PSI with additional gap balancing ( PSI-GB ) ( n = 25 ) . All patients were clinical ly examined at 3 and 12 months postoperatively . Data on the range of motion , the Knee Society Score , the Western Ontario and McMasters Universities Osteoarthritis Index , the High-Flexion Knee Score ( HFKS ) , and the Forgotten Joint Score ( FJS ) were compiled at follow-up . Statistically significant improvements were found for all clinical parameters in the PSI-GB group compared to the PSI-S group at 3 months postoperatively and for FS , FJS , and HFKS at 12 months . However , the relevance of these differences , as well as their effect on long-term outcomes , needs to be evaluated further . In conclusion , patient-specific instrumentation combined with gap balancing yielded good early clinical outcomes BACKGROUND Measured resection ( MR ) and gap balancing ( GB ) are common surgical techniques for total knee arthroplasty ( TKA ) . Controversy has arisen as each conceptually differs in how the knee is balanced through bone and soft tissue management . The objective of the present study was to compare both the frequency of condylar liftoff and the location of femorotibial contact from extension through midflexion between patients undergoing GB or MR TKA . METHODS A total of 24 knees ( 23 patients ) were r and omly assigned at referral to either a surgeon performing MR or GB TKA  with the same single radius , posterior-stabilized implant ( 12 per cohort ) . At 1-year postoperation , patients underwent biplanar radiographic imaging at 0 ° , 20 ° , 40 ° , and 60 ° of flexion  . Condylar liftoff , contact location , and magnitude of excursion on each condyle were measured . Preoperative and postoperative clinical outcome scores were also collected . RESULTS There was no difference ( P = .41 ) in the frequency of liftoff between cohorts . The MR cohort had more posterior contact on the medial condyle ( P < .01 ) and more anterior contact on the lateral condyle ( P < .01 ) throughout flexion . Motion patterns were similar between cohorts , with similar medial ( P = .48 ) and lateral ( P = .44 ) excursion , which was equal in magnitude between condyles for both MR ( P = .48 ) and GB ( P = .73 ) . There was no difference in clinical outcome scores between groups . CONCLUSION For this particular implant system 
    Output:
    
agent
The EKA Femoral Rotation Focus Group has not identified a single best reference method to determine femoral component rotation , but surgeons mostly prefer the measured resection technique using at least two l and marks for cross-checking the rotation .
***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: Two surgical strategies are possible in total knee arthroplasty ( TKA ) : a measured resection technique , in which bone l and marks are used to guide resections equal to the distal and posterior thickness of the femoral component , or a gap-balancing approach , in which equal collateral ligament tension in flexion and extension is sought before and as a guide to final bone cuts . In this study performed with computer assisted system , we compared the 2 different methods in 126 patients followed prospect ively in order to analyze the effect of both the techniques on joint-line ( JL ) maintenance , axial limb restoration and components position . The gap technique showed a statistical increase in the post-operative value when compared with the measured resection technique , ( P = 0.008 ) . When comparing the two groups regarding to the pre-operative deformity , we have found a statistical difference ( P = 0.001 ) in case of moderate pre-operative deformity ( less than 10 ° ) , and the measured resection technique showed a slight superiority in preserving a joint line more faithful to the pre-operative . We found an ideal alignment for the mechanical axis ( 180 ° ± 3 ° ) ( 95 % of cases ) . In six cases ( 5 % ) , the mean post-operative value exceeded ( varus or valgus ) the ideal value by more than 3 ° . In the frontal plane , a good alignment was observed for both femoral and tibial components without a significant difference between the two techniques . In the sagittal plane was found more alignment variability due to the different implants used and their ideal starting slope , from 7 ° to 3 ° . Finally , the surgeon can use the approach with which he has more confidence ; however , as the measured resection technique causes less reduction in the post-operative joint-line position , in case of shortening of patellar tendon or patella infera , this technique is preferable A total knee arthroplasty can be completed using two techniques ; measured resection or gap balancing . A prospect i ve blinded r and omized controlled trial was completed with 103 patients r and omized to measured resection ( n = 52 ) or gap balancing ( n = 51 ) . Primary outcome measure was femoral component rotation . Secondary outcome measures were joint-line change , gap symmetry and function and quality -of-life outcomes .  Gap balancing result ed in a significantly raised joint-line compared to measured resection .  Gap symmetry was significantly better using gap balancing .  Functional outcomes and quality -of-life were not significantly different at 24 months . Using computer navigation , gap balancing significantly raises the joint-line in order to improve gap symmetry . This does not result in a clinical difference in function or quality of life at 24 months Purpose The optimal coronal alignment is still under debate . However , in most of the studies , alignment was only assessed using radiographs , which are not accurate enough for assessment of tibial and femoral TKA position . The primary purpose of this study was to assess the relationship between coronal TKA alignment using 3D-reconstructed CTs and clinical outcome in patients with preoperative varus in comparison with patients with natural or valgus deformity . It was the hypothesis that neutral limb alignment shows a better outcome after TKA . Methods Prospect ively collected data of 38 patients were included . The clinical and radiological follow-up was 24 months . The patients were grouped into two groups with regard to their preoperative limb alignment . Group A ( varus ) consisted of 21 patients with preoperative varus of 3 ° or more , while group B ( non-varus ) consisted of 17 patients with  neutral  ( − 3 < 0 > + 3 ) or valgus alignment ( > + 3 ) . For assessment of TKA component position and orientation , 3D-reconstructed CT was used . The measurements of the deviation from the whole limb mechanical axis ( HKA angle ) and the joint line alignment in the femoral ( mLDFA ) and the tibial side ( MPTA ) were assessed in the preoperative leg as well as during follow-up after TKA . For clinical outcome assessment , the Knee Society Score ( KSS ) was used at 1 and 2 years postoperatively . Correlation between KSS score and each variable was done using a linear and quadratic regression model ( p < 0.05 ) . Results The mean postoperative HKA angle was − 1.3 ( varus ) in the varus group and + 1.4 ( valgus ) in the non-varus group . Overall , significant correlations between the preoperative and postoperative alignments were found . In the preoperatively non-varus group , a highly significant correlation was found between neutral limb alignment ( HKA = 0 ° ± 3 ° ) and higher KSS ( r2 = 0.74 , p = 0.00 ) . In the varus group , no correlation was found between the postoperative whole limb alignment and the components ’ position in the coronal plane to KSS score . Conclusion A significant correlation was found between neutral limb alignment and higher KSS only in patients with preoperative non-varus alignment . The concept of constitutional varus alignment is still under debate . Moreover , it appears that one should aim for a more individualized , alignment target based on the individual knee morphotype . Level of evidence Diagnostic study , Level II Background Femoral component rotation ( FCR ) is one of the most important factors in total knee arthroplasty . In this prospect i ve study , we used three different techniques for FCR and analyzed their accuracy with postoperative axial computed tomography ( CT ) images . We also evaluated effect of FCR to clinical outcome . Methods One hundred sixty-five patients were r and omly allocated into three groups . In the measured resection group , FCR was set by externally rotating the axis 3 ° off the posterior femoral condylar axis . In the tensor group , a gap-tensioning device set at 20 lbf was used . In the block group , spacer blocks of various thicknesses were used . The FCR angle ( FCRa ) was measured on postoperative axial CT as an angle between the clinical transepicondylar and posterior condylar axes of the femoral component . Outliers were defined as FCRas deviated more than 3 ° either internally or externally . Postoperative 2 year clinical scores and knee range of motion were checked . Results The tensor group had significantly better positioning of the femoral component to the neutral position compared with the measured resection group and the block group ( mean FCRa : internal rotation 1.79 , 0.43 and 2.63 ° , respectively , p < 0.001 ) . The outliers were also least frequent in the tensor group ( 35 , 16 and 40 % , respectively , p = 0.02 ) . There were no significant differences in postoperative 2 year clinical results among groups . Conclusions Gap technique with a 20-lbf tensor device was the most accurate and precise method for obtaining adequate FCR . Measured resection with 3 ° external rotation and gap technique with blocks could lead to internal rotation of the femoral component . Postoperative 2 year clinical results were not significantly different among groups with different techniques for FCR.Trial registration The study was registered in the Clinical Research information Service ( trial number : KCT0000129 ) in Korea . Registration date is 23rd of June , 2011 Purpose As patellar tracking and loading is influenced by tibial tuberosity and trochlear groove ( TT – TG ) distance , patellar height , thickness and tilt as well as TKA component position , it was our hypothesis that these parameters significantly correlate with patellar BTU intensity and localization in SPECT/CT . The purpose of the study was to investigate whether TKA component position as well as the height , thickness and tilt of the unresurfaced patella influences the intensity and the distribution pattern of BTU in SPECT/CT . Methods A total of 62 consecutive patients who underwent primary TKA without patellar resurfacing were prospect ively included . Demographic data such as age , gender , side and type of primary TKA were noted . All patients underwent clinical and radiological examination  in a specialized knee clinic , including st and ardized radiographs ( anterior – posterior and lateral weight bearing , patellar skyline view ) and Tc-99m-HDP-SPECT/CT before , 12 and 24 months after TKA . SPECT/CT images were analysed on 3D reconstructed images . Rotational , sagittal and coronal position of the tibial and femoral TKA components was assessed using a previously vali date d analysis software . Measurements of BTU including intensity and anatomical distribution pattern were also performed from 3D data . The patellar height , thickness and tilt were measured , and the distance between TT and TG was measured using axial CT images . Univariate analysis was performed to identify any correlations between BTU and TKA component position and patellar measurements ( p < 0.05 ) . Results The highest median BTU was measured in the superior posterior parts of the patella . A statistically significant correlation was found between valgus alignment of the femoral TKA and increased BTU at the lateral patellar regions ( p < 0.05 ) . External rotation of the tibial TKA correlated with increased BTU at the lateral superior joint adjacent part ( p < 0.05 ) . No correlation was found between the tibial TKA  position ( varus – valgus , anterior and posterior slope ) , TT – TG distance , patellar height and patellar BTU values . Conclusions A significant correlation of increased patellar BTU was found with femoral valgus TKA alignment . These findings highlight the importance of femoral TKA position in coronal plane with regard to post-operative patellar tracking . Moreover , these facts might explain anterior knee pain in unhappy TKA with femoral valgus alignment . Level of evidence Diagnostic study , Level II BACKGROUND For establishing femoral component position , gap-balancing ( GB ) and measured resection ( MR ) techniques were compared using a force sensor . METHODS Ninety-one patients were r and omized to undergo primary total knee arthroplasty using either MR ( n = 43 ) or GB ( n = 48 ) technique using a single total knee arthroplasty design .  GB was performed with an instrumented tensioner . Force sensor data were obtained before the final implantation . RESULTS GB result ed in greater range of femoral component rotation vs MR ( 1.5 ° ± 2.9 ° vs 3.1 ° ± 0.5 ° , P < .05 ) and posterior condylar cut thickness medially ( 10.2 ± 2.0 mm vs 9.0 ± 1.3 mm ) and laterally ( 8.5 ± 1.9 mm vs 6.4 ± 1.0 mm ) . Force sensor data showed a decreased intercompartmental force difference at full flexion in GB ( .8 ± 2.3 vs 2.0 ± 3.3u , 1u ≈ 15 N , P < .05 ) . CONCLUSION GB result ed in a greater range of femoral component rotation and thicker posterior condylar cuts result ing in an increased flexion space relative to MR . Intercompartmental force difference trended toward a more uniform distribution between full extension and full flexion in the GB vs MR group While patient-specific instrumentation ( PSI ) in total knee arthroplasty ( TKA ) allows for transfer of the preoperative plan onto bony l and marks , the soft tissue balancing is not affected . The goals of this r and omized clinical trial were to compare PSI and the measured resection technique ( conventional ) with PSI and the gap balancing technique .  Fifty patients were r and omized to TKA with conventional PSI ( PSI-S ) ( n = 25 ) or to PSI with additional gap balancing ( PSI-GB ) ( n = 25 ) . All patients were clinical ly examined at 3 and 12 months postoperatively . Data on the range of motion , the Knee Society Score , the Western Ontario and McMasters Universities Osteoarthritis Index , the High-Flexion Knee Score ( HFKS ) , and the Forgotten Joint Score ( FJS ) were compiled at follow-up . Statistically significant improvements were found for all clinical parameters in the PSI-GB group compared to the PSI-S group at 3 months postoperatively and for FS , FJS , and HFKS at 12 months . However , the relevance of these differences , as well as their effect on long-term outcomes , needs to be evaluated further . In conclusion , patient-specific instrumentation combined with gap balancing yielded good early clinical outcomes BACKGROUND Measured resection ( MR ) and gap balancing ( GB ) are common surgical techniques for total knee arthroplasty ( TKA ) . Controversy has arisen as each conceptually differs in how the knee is balanced through bone and soft tissue management . The objective of the present study was to compare both the frequency of condylar liftoff and the location of femorotibial contact from extension through midflexion between patients undergoing GB or MR TKA . METHODS A total of 24 knees ( 23 patients ) were r and omly assigned at referral to either a surgeon performing MR or GB TKA  with the same single radius , posterior-stabilized implant ( 12 per cohort ) . At 1-year postoperation , patients underwent biplanar radiographic imaging at 0 ° , 20 ° , 40 ° , and 60 ° of flexion  . Condylar liftoff , contact location , and magnitude of excursion on each condyle were measured . Preoperative and postoperative clinical outcome scores were also collected . RESULTS There was no difference ( P = .41 ) in the frequency of liftoff between cohorts . The MR cohort had more posterior contact on the medial condyle ( P < .01 ) and more anterior contact on the lateral condyle ( P < .01 ) throughout flexion . Motion patterns were similar between cohorts , with similar medial ( P = .48 ) and lateral ( P = .44 ) excursion , which was equal in magnitude between condyles for both MR ( P = .48 ) and GB ( P = .73 ) . There was no difference in clinical outcome scores between groups . CONCLUSION For this particular implant system 
    Output:
    