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: Purpose Restoration of correct alignment is one of the main objectives of total knee arthroplasty ( TKA ) . However , the influence of residual malalignment on clinical and functional outcomes is currently uncertain . This study was therefore undertaken to ascertain its influence in patients undergoing TKA for varus osteoarthritis of the knee . Methods A cohort of 132 consecutive patients ( 143 knees ) with pre-operative varus alignment was evaluated with a mean follow-up period of 7.2 years . Based upon the post-operative alignment , patients were stratified into three groups : neutral , mild varus , and severe varus . These groups were compared with respect to clinical and functional outcomes . Results All patients had post-operative improvements in Knee Society Score ( KSS ) . Knees that were left in mild varus scored significantly better for the KSS and the Western Ontario and McMaster Universities Arthritis Index , compared with knees that were corrected to neutral and knees that were left in severe varus exceeding 6 ° . No revisions occurred in any of the groups at midterm follow-up . Conclusion The results of this study contradict the conventional assumption that correction to neutral mechanical alignment leads to the best outcome following TKA . Patients with pre-operative varus had better clinical and functional outcome scores if the alignment was left in mild varus , as compared with patients with an alignment correction to neutral . Level of evidence Therapeutic study , Level III Background Kinematically aligned TKA restores function by aligning the femoral and tibial components to the normal or prearthritic joint lines of the knee . However , aligning the components to the joint lines of the normal knee also aligns the tibial component in varus , creating concern that varus alignment might result in poor function and early catastrophic failure . Questions / Purpose sWe therefore determined whether function and the incidence of catastrophic failure were different when the tibial component , knee , and limb alignment were in a specified normal range , varus outlier , or valgus outlier . Methods We prospect ively followed all 198 patients ( 214 knees ) who underwent TKAs between February and October 2008 . We treated each knee in this cohort of patients with a kinematically aligned , cruciate-retaining prosthesis implanted using patient-specific guides . From a long-leg scanogram , we measured and categorized alignment of the tibial component as in range ( ≤ 0 ° ) or a varus outlier ( > 0 ° ) , alignment of the knee as in range ( between −2.5 ° to −7.4 ° valgus ) or a varus ( > −2.5 ° ) or valgus ( < −7.4 ° ) outlier , and alignment of the limb as in range ( 0 ° ± 3 ° ) or a varus ( > 3 ° ) or valgus ( < −3 ° ) outlier . We assessed function using the Oxford Knee Score and WOMAC ™ score , and reported catastrophic failure as the incidence of revision attributable to loosening , wear , and instability of the femoral or tibial components . The minimum followup was 31 months ( mean , 38 months ; range , 31–43 months ) . Results The mean Oxford Knee Score of 43 and WOMAC ™ score of 92 were similar between the three alignment categories . The incidence of catastrophic failure in each alignment category was zero . Conclusions Kinematically aligned TKA restores function without catastrophic failure regardless of the alignment category . Because 75 % of patients had their tibial component categorized as a varus outlier and also had high function and a zero incidence of catastrophic failure , the concern that kinematic alignment compromises function and places the components at a high risk for catastrophic failure is unfounded and should be of interest to surgeons committed to cutting the tibia perpendicular to the mechanical axis of the tibia . Level of Evidence Level IV , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Purpose To compare the femoral and tibial components rotational alignment in total knee arthroplasty ( TKA ) performed either with conventional or with patient-specific instrumentation . Methods Forty-five patients underwent primary TKA and were prospect ively r and omized into two groups : 22 patients into the conventional instrumentation group ( group A ) and 23 patients into the Signature ™ patient-specific instrumentation group ( group B ) . All patients underwent computed tomography of the operated knee in the first week after surgery to measure  the components rotation . Results The femoral component rotation was 0.0 ° ( −0.25 , 1.0 ) in group A , and 0.0 ° ( 0.0 , 1.0 ) in group B. The tibial component rotation was −16.0 ° ( −18.5 , 11.8 ) in group A , and −16.0 ° ( −19.0 , −14.0 ) in group B. There were no significant differences between the two groups in tibial and femoral components rotation . The difference between the tibial component rotation and the neutral tibial rotation was similar in both groups [ 2.0 ° ( −0.5 , 6.3 ) in group A and 2.0 ° ( −1.0 , 4.0 ) in group B ] , but the dispersion around the median was different between the two groups . The amplitude of the difference between tibial rotation and neutral position was 27 ° ( −13 , 14 ) in group A and 9 ° ( −3 , 6 ) in group B. Conclusions There is a smaller chance of internal malrotation of the tibial component with the Signature ™ patient-specific instrumentation system , with less dispersion and amplitude of the tibial component rotation around the neutral position . Level of evidence II Abstract Purpose It was our hypothesis that patient-specific instrumentation ( PSI ) can improve the accuracy of the rotational alignment in TKA based on the concept of the system and on the potential to clearly identify pre-operatively during planning the classical anatomical l and marks that serve as references to set-up the rotation both for the femur and tibia . Material s and methods In this prospect i ve comparative r and omized study , 40 patients ( 20 in each group ) operated in our institution between September 2012 and January 2013 by the 2 senior authors were included . R and omization of patients into one of the two groups was done by the Hospital Informatics Department with the use of a systematic sampling method . All patients received the same cemented high-flex mobile bearing TKA . In the PSI group , implant position was compared to the planed position using previously vali date d dedicated software . The position of the implants ( frontal and sagittal ) was compared in the 2 groups on st and ard X-rays , and the rotational position was analysed on post-operative CT-scan . Results 90 % of the patients add < 2 ° or mm of difference between the planned position of the implants and the obtained position , except for the tibial rotation where the variations were much higher . Mean HKA was 179 ° ( 171–185 ) in the PSI group with 4 outliers ( 2 varus : 171 ° and 172 ° :184 ° and 185 ° ) and 178.3 ° with 2 outliers ( 171 ° and 176 ° ) in the control group . No difference was observed between the two groups concerning the frontal and sagittal position of the implants on the ML and AP X-rays . No significant difference of femoral rotation was observed between the two groups with a mean of 0.4 ° in the PSI group and 0.2 ° in the control group ( p : n.s ) . Mean tibial rotation was 8 ° of internal rotation in the PSI group and 15 ° of internal rotation in the st and ard group ( p : n.s ) . Conclusion Based on our results , we were unable to confirm our hypothesis as PSI can not improve rotation in TKA . More work needs to be done to more clearly define the place of PSI in TKA , to keep on improving the accuracy of the system and to better define the individual targets in TKA in terms of frontal , sagittal and rotational positioning of the implant for each patient . Level of evidence Prospect i ve comparative r and omized study , Level II Background Recently , patient-specific guides ( PSGs ) have been introduced , cl aim ing a significant improvement in accuracy and reproducibility of component positioning in TKA . Despite intensive marketing by the manufacturers , this cl aim has not yet been confirmed in a controlled prospect i ve trial . Questions / purpose sWe ( 1 ) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and ( 2 ) logged the need for applying changes in the suggested position of the PSG . Methods In this r and omized controlled trial , we enrolled 128 patients . In the PSG cohort , surgical navigation was used as an intraoperative control . When the suggested cut deviated more than 3 ° from target , the use of PSG was ab and oned and marked as an outlier . When cranial-caudal position or size was adapted , the PSG was marked as modified . All patients underwent long-leg st and ing radiography and CT scan .  Deviation of more than 3 ° from the target in any plane was defined as an outlier . Results The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment ( 25 % versus 28 % ; p = 0.69 ) , femoral coronal alignment ( 7 % versus 14 % ) ( p = 0.24 ) , and femoral axial alignment ( 23 % versus 17 % ; p = 0.50 ) . There were more outliers in tibial coronal ( 15 % versus 3 % ; p = 0.03 ) and sagittal 21 % versus 3 % ; p = 0.002 ) alignment in the PSG group than in the conventional group . PSGs were ab and oned in 14 patients ( 22 % ) and modified in 18 ( 28 % ) . Conclusions PSGs do not improve accuracy in TKA and , in our experience , were somewhat impractical in that the procedure needed to be either modified or ab and oned with some frequency . Level of Evidence Level I , therapeutic study . See instructions for authors for a complete description of levels of evidence Background : The purpose of this study was threefold : ( 1 ) to determine the scientific quality of published r and omized trials in the American Volume of The Journal of Bone and Joint Surgery from 1988 through 2000 , ( 2 ) to identify predictors of study quality , and ( 3 ) to evaluate inter-rater agreement in the scoring of study quality with use of a simple scale . Methods : H and search es of The Journal of Bone and Joint Surgery were conducted in duplicate to identify r and omized clinical trials . Of 2468 studies identified , seventy-two ( 2.9 % ) met all eligibility criteria . Two investigators each assessed the quality of the study under blinded conditions and abstract ed relevant data . Results : The mean score ( and st and ard error ) for the quality of the seventy-two r and omized trials was 68.1 % ± 1.6 % ; 60 % ( forty-three ) scored < 75 % . Drug trials had a significantly higher mean quality score than did surgical trials ( 72.8 % compared with 63.9 % , p < 0.05 ) . Regression analysis revealed that cited affiliation with an epidemiology department and cited funding were associated with higher quality scores . Failure to conceal r and omization , to blind outcome assessors , and to describe why patients were excluded result ed in significantly lower quality scores ( p < 0.05 ) , more than the 5 % decrease expected by removal of each item . A priori calculations of sample size were rarely performed in the review ed studies , and only 2 % of the studies with negative results included a post hoc power analysis . The Detsky quality scale met accepted st and ards of interobserver reliability ( kappa , 0.87 ; 95 % confidence interval , 0.70 to 0.95 ) . Conclusions : Few studies published in The Journal of Bone and Joint Surgery were r and omized trials . More than half of the trials were limited by a lack of concealed r and omization , lack of blinding of outcome assessors , or failure to report reasons for excluding patients . Application of st and ardized guidelines for the reporting of clinical trials in orthopaedics should improve quality Purpose This prospect i ve , double-blind , r and omised controlled trial was design ed to address the following research questions : firstly , is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA . Secondly , is there a significant difference in operation time , blood loss and length of hospital stay between the two techniques . We hypothesise that there will be fewer outliers with PSG TKA and that operation time , blood loss and length of hospital stay can be significantly reduced with PSG . Methods A total of 180 patients were r and omised for PSG TKA ( group 1 ) or conventional TKA ( group 2 ) in two centres . Patients were stratified per hospital . Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on digital , st and ing , long-leg and st and ard lateral radiographs by two independent outcome assessors in both centres . Percentages of outliers ( > 3 ° ) were determined . We compared blood loss , operation time and length of hospital stay . Results There was no statistically significant difference in mean mechanical axis or outliers in mechanical axis between groups . No statistically significant difference was found for the alignment of the individual components in the frontal plane nor for the percentages of outliers . There was a statistically significant difference in outliers for the femoral component in the sagittal plane , with a higher percentage of outliers in the group 1 ( p = 0.017 ) . No such significant result was found for the tibial component in that plane . All interclass correlation coefficients were good . Blood loss was 100 mL less in group 1 ( p < 0.001 ) . Operation time was 5 min shorter in group 1 ( p < 0.001 ) . Length of hospital stay was identical with a mean of 3.6 days ( p = 0.657 ) . Conclusions The results in terms of obtaining a 
    Output:
    
agent
We conclude that PSI does not improve the accuracy of alignment of the components in TKR compared with conventional instrumentation
***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: Purpose Restoration of correct alignment is one of the main objectives of total knee arthroplasty ( TKA ) . However , the influence of residual malalignment on clinical and functional outcomes is currently uncertain . This study was therefore undertaken to ascertain its influence in patients undergoing TKA for varus osteoarthritis of the knee . Methods A cohort of 132 consecutive patients ( 143 knees ) with pre-operative varus alignment was evaluated with a mean follow-up period of 7.2 years . Based upon the post-operative alignment , patients were stratified into three groups : neutral , mild varus , and severe varus . These groups were compared with respect to clinical and functional outcomes . Results All patients had post-operative improvements in Knee Society Score ( KSS ) . Knees that were left in mild varus scored significantly better for the KSS and the Western Ontario and McMaster Universities Arthritis Index , compared with knees that were corrected to neutral and knees that were left in severe varus exceeding 6 ° . No revisions occurred in any of the groups at midterm follow-up . Conclusion The results of this study contradict the conventional assumption that correction to neutral mechanical alignment leads to the best outcome following TKA . Patients with pre-operative varus had better clinical and functional outcome scores if the alignment was left in mild varus , as compared with patients with an alignment correction to neutral . Level of evidence Therapeutic study , Level III Background Kinematically aligned TKA restores function by aligning the femoral and tibial components to the normal or prearthritic joint lines of the knee . However , aligning the components to the joint lines of the normal knee also aligns the tibial component in varus , creating concern that varus alignment might result in poor function and early catastrophic failure . Questions / Purpose sWe therefore determined whether function and the incidence of catastrophic failure were different when the tibial component , knee , and limb alignment were in a specified normal range , varus outlier , or valgus outlier . Methods We prospect ively followed all 198 patients ( 214 knees ) who underwent TKAs between February and October 2008 . We treated each knee in this cohort of patients with a kinematically aligned , cruciate-retaining prosthesis implanted using patient-specific guides . From a long-leg scanogram , we measured and categorized alignment of the tibial component as in range ( ≤ 0 ° ) or a varus outlier ( > 0 ° ) , alignment of the knee as in range ( between −2.5 ° to −7.4 ° valgus ) or a varus ( > −2.5 ° ) or valgus ( < −7.4 ° ) outlier , and alignment of the limb as in range ( 0 ° ± 3 ° ) or a varus ( > 3 ° ) or valgus ( < −3 ° ) outlier . We assessed function using the Oxford Knee Score and WOMAC ™ score , and reported catastrophic failure as the incidence of revision attributable to loosening , wear , and instability of the femoral or tibial components . The minimum followup was 31 months ( mean , 38 months ; range , 31–43 months ) . Results The mean Oxford Knee Score of 43 and WOMAC ™ score of 92 were similar between the three alignment categories . The incidence of catastrophic failure in each alignment category was zero . Conclusions Kinematically aligned TKA restores function without catastrophic failure regardless of the alignment category . Because 75 % of patients had their tibial component categorized as a varus outlier and also had high function and a zero incidence of catastrophic failure , the concern that kinematic alignment compromises function and places the components at a high risk for catastrophic failure is unfounded and should be of interest to surgeons committed to cutting the tibia perpendicular to the mechanical axis of the tibia . Level of Evidence Level IV , therapeutic study . See Guidelines for Authors for a complete description of levels of evidence Purpose To compare the femoral and tibial components rotational alignment in total knee arthroplasty ( TKA ) performed either with conventional or with patient-specific instrumentation . Methods Forty-five patients underwent primary TKA and were prospect ively r and omized into two groups : 22 patients into the conventional instrumentation group ( group A ) and 23 patients into the Signature ™ patient-specific instrumentation group ( group B ) . All patients underwent computed tomography of the operated knee in the first week after surgery to measure  the components rotation . Results The femoral component rotation was 0.0 ° ( −0.25 , 1.0 ) in group A , and 0.0 ° ( 0.0 , 1.0 ) in group B. The tibial component rotation was −16.0 ° ( −18.5 , 11.8 ) in group A , and −16.0 ° ( −19.0 , −14.0 ) in group B. There were no significant differences between the two groups in tibial and femoral components rotation . The difference between the tibial component rotation and the neutral tibial rotation was similar in both groups [ 2.0 ° ( −0.5 , 6.3 ) in group A and 2.0 ° ( −1.0 , 4.0 ) in group B ] , but the dispersion around the median was different between the two groups . The amplitude of the difference between tibial rotation and neutral position was 27 ° ( −13 , 14 ) in group A and 9 ° ( −3 , 6 ) in group B. Conclusions There is a smaller chance of internal malrotation of the tibial component with the Signature ™ patient-specific instrumentation system , with less dispersion and amplitude of the tibial component rotation around the neutral position . Level of evidence II Abstract Purpose It was our hypothesis that patient-specific instrumentation ( PSI ) can improve the accuracy of the rotational alignment in TKA based on the concept of the system and on the potential to clearly identify pre-operatively during planning the classical anatomical l and marks that serve as references to set-up the rotation both for the femur and tibia . Material s and methods In this prospect i ve comparative r and omized study , 40 patients ( 20 in each group ) operated in our institution between September 2012 and January 2013 by the 2 senior authors were included . R and omization of patients into one of the two groups was done by the Hospital Informatics Department with the use of a systematic sampling method . All patients received the same cemented high-flex mobile bearing TKA . In the PSI group , implant position was compared to the planed position using previously vali date d dedicated software . The position of the implants ( frontal and sagittal ) was compared in the 2 groups on st and ard X-rays , and the rotational position was analysed on post-operative CT-scan . Results 90 % of the patients add < 2 ° or mm of difference between the planned position of the implants and the obtained position , except for the tibial rotation where the variations were much higher . Mean HKA was 179 ° ( 171–185 ) in the PSI group with 4 outliers ( 2 varus : 171 ° and 172 ° :184 ° and 185 ° ) and 178.3 ° with 2 outliers ( 171 ° and 176 ° ) in the control group . No difference was observed between the two groups concerning the frontal and sagittal position of the implants on the ML and AP X-rays . No significant difference of femoral rotation was observed between the two groups with a mean of 0.4 ° in the PSI group and 0.2 ° in the control group ( p : n.s ) . Mean tibial rotation was 8 ° of internal rotation in the PSI group and 15 ° of internal rotation in the st and ard group ( p : n.s ) . Conclusion Based on our results , we were unable to confirm our hypothesis as PSI can not improve rotation in TKA . More work needs to be done to more clearly define the place of PSI in TKA , to keep on improving the accuracy of the system and to better define the individual targets in TKA in terms of frontal , sagittal and rotational positioning of the implant for each patient . Level of evidence Prospect i ve comparative r and omized study , Level II Background Recently , patient-specific guides ( PSGs ) have been introduced , cl aim ing a significant improvement in accuracy and reproducibility of component positioning in TKA . Despite intensive marketing by the manufacturers , this cl aim has not yet been confirmed in a controlled prospect i ve trial . Questions / purpose sWe ( 1 ) compared three-planar component alignment and overall coronal mechanical alignment between PSG and conventional instrumentation and ( 2 ) logged the need for applying changes in the suggested position of the PSG . Methods In this r and omized controlled trial , we enrolled 128 patients . In the PSG cohort , surgical navigation was used as an intraoperative control . When the suggested cut deviated more than 3 ° from target , the use of PSG was ab and oned and marked as an outlier . When cranial-caudal position or size was adapted , the PSG was marked as modified . All patients underwent long-leg st and ing radiography and CT scan .  Deviation of more than 3 ° from the target in any plane was defined as an outlier . Results The PSG and conventional cohorts showed similar numbers of outliers in overall coronal alignment ( 25 % versus 28 % ; p = 0.69 ) , femoral coronal alignment ( 7 % versus 14 % ) ( p = 0.24 ) , and femoral axial alignment ( 23 % versus 17 % ; p = 0.50 ) . There were more outliers in tibial coronal ( 15 % versus 3 % ; p = 0.03 ) and sagittal 21 % versus 3 % ; p = 0.002 ) alignment in the PSG group than in the conventional group . PSGs were ab and oned in 14 patients ( 22 % ) and modified in 18 ( 28 % ) . Conclusions PSGs do not improve accuracy in TKA and , in our experience , were somewhat impractical in that the procedure needed to be either modified or ab and oned with some frequency . Level of Evidence Level I , therapeutic study . See instructions for authors for a complete description of levels of evidence Background : The purpose of this study was threefold : ( 1 ) to determine the scientific quality of published r and omized trials in the American Volume of The Journal of Bone and Joint Surgery from 1988 through 2000 , ( 2 ) to identify predictors of study quality , and ( 3 ) to evaluate inter-rater agreement in the scoring of study quality with use of a simple scale . Methods : H and search es of The Journal of Bone and Joint Surgery were conducted in duplicate to identify r and omized clinical trials . Of 2468 studies identified , seventy-two ( 2.9 % ) met all eligibility criteria . Two investigators each assessed the quality of the study under blinded conditions and abstract ed relevant data . Results : The mean score ( and st and ard error ) for the quality of the seventy-two r and omized trials was 68.1 % ± 1.6 % ; 60 % ( forty-three ) scored < 75 % . Drug trials had a significantly higher mean quality score than did surgical trials ( 72.8 % compared with 63.9 % , p < 0.05 ) . Regression analysis revealed that cited affiliation with an epidemiology department and cited funding were associated with higher quality scores . Failure to conceal r and omization , to blind outcome assessors , and to describe why patients were excluded result ed in significantly lower quality scores ( p < 0.05 ) , more than the 5 % decrease expected by removal of each item . A priori calculations of sample size were rarely performed in the review ed studies , and only 2 % of the studies with negative results included a post hoc power analysis . The Detsky quality scale met accepted st and ards of interobserver reliability ( kappa , 0.87 ; 95 % confidence interval , 0.70 to 0.95 ) . Conclusions : Few studies published in The Journal of Bone and Joint Surgery were r and omized trials . More than half of the trials were limited by a lack of concealed r and omization , lack of blinding of outcome assessors , or failure to report reasons for excluding patients . Application of st and ardized guidelines for the reporting of clinical trials in orthopaedics should improve quality Purpose This prospect i ve , double-blind , r and omised controlled trial was design ed to address the following research questions : firstly , is there a significant difference in outliers in alignment in the frontal and sagittal plane between PSG TKA and conventional TKA . Secondly , is there a significant difference in operation time , blood loss and length of hospital stay between the two techniques . We hypothesise that there will be fewer outliers with PSG TKA and that operation time , blood loss and length of hospital stay can be significantly reduced with PSG . Methods A total of 180 patients were r and omised for PSG TKA ( group 1 ) or conventional TKA ( group 2 ) in two centres . Patients were stratified per hospital . Alignment of the mechanical axis of the leg and flexion/extension and varus/valgus of the individual prosthesis components were measured on digital , st and ing , long-leg and st and ard lateral radiographs by two independent outcome assessors in both centres . Percentages of outliers ( > 3 ° ) were determined . We compared blood loss , operation time and length of hospital stay . Results There was no statistically significant difference in mean mechanical axis or outliers in mechanical axis between groups . No statistically significant difference was found for the alignment of the individual components in the frontal plane nor for the percentages of outliers . There was a statistically significant difference in outliers for the femoral component in the sagittal plane , with a higher percentage of outliers in the group 1 ( p = 0.017 ) . No such significant result was found for the tibial component in that plane . All interclass correlation coefficients were good . Blood loss was 100 mL less in group 1 ( p < 0.001 ) . Operation time was 5 min shorter in group 1 ( p < 0.001 ) . Length of hospital stay was identical with a mean of 3.6 days ( p = 0.657 ) . Conclusions The results in terms of obtaining a 
    Output:
    