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 Long-leg radiographs ( LLR ) are often used in orthopaedics to assess limb alignment in patients undergoing total knee arthroplasty ( TKA ) . However , there are still concerns about the adequacy of measurements performed on LLR . We assessed the reliability and validity of measurements on LLR using three-dimensional computed tomography ( 3D CT)-scan as a gold st and ard . METHODS Six different surgeons measured the mechanical axis and position of the femoral and tibial components individually on 24 LLR .  Intraclass correlation coefficients ( ICC ) were calculated to obtain reliability and Bl and -Altman plots were constructed to assess agreement between measurements on LLR and measurements on 3D CT-scan . RESULTS ICC agreement for the six observer measurements on LLR was 0.70 for the femoral component and 0.80 for the tibial component . The mean difference between measurements performed on LLR and 3D CT-scan was 0.3 ° for the femoral component and -1.1 ° for the tibial component . Variation of the difference between LLR and 3D CT-scan for the femoral component was 1.1 ° and 0.9 ° for the tibial component . 95 % of the differences between measurements performed on LLR and 3D CT-scan were between -1.9 and 2.4 ° ( femoral component ) and between -2.9 and 0.7 ( tibial component ) . CONCLUSION Measurements on LLR show moderate to good reliability and , when compared to 3D CT-scan , show good validity . CLINICAL TRIAL REGISTRATION NUMBER institutional review board Atrium-Orbis-Zuyd , number : 11-T-15 . LEVEL OF EVIDENCE Prospect i ve cohort study , Level II 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 Patient-specific femoral and tibial cutting blocks produced with use of data from preoperative computed tomography ( CT ) or magnetic resonance imaging ( MRI ) scans have been employed recently to optimize component alignment in total knee arthroplasty . We report the results of a r and omized controlled trial in which CT scans were used to compare postoperative component alignment between patients treated with custom instruments  and those managed with traditional instruments . METHODS The in-hospital data and early clinical outcomes , including Knee Society scores , were determined in a r and omized clinical trial of forty-seven patients who had undergone a total of forty-eight primary total knee arthroplasties with patient-specific instruments ( twenty-two knees ) or st and ard instruments ( twenty-six knees ) . Orientation of the implants was compared by using three-dimensional CT data . RESULTS No significant differences were found between the study and control groups with respect to any clinical outcome after a minimum of six months of follow-up . The patient-specific tibial cutting block was ab and oned in favor of a st and ard external alignment jig in seven of the twenty-two study knees because of possible malalignment . A detailed analysis of intent-to-treat and per- protocol groups of study and control knees did not show any significant improvement in component alignment , including femoral component rotation in the axial plane , in the patients treated with the custom instruments . The percentage of outliers -- defined as less than -3 ° or more than 3 ° from the correct orientation of the tibial slope -- was significantly higher in the group treated with use of patient-specific blocks than it was in the control group , in both the intent-to-treat ( 32 % versus 8 % , p = 0.032 ) and the per- protocol ( 47 % versus 6 % , p = 0.0008 ) analysis . CONCLUSIONS There were no significant improvements in clinical outcomes or knee component alignment in patients treated with patient-specific cutting blocks as compared with those treated with st and ard instruments . The group treated with patient-specific cutting blocks had a significantly higher prevalence of malalignment in terms of tibial component slope than the knees treated with st and ard instruments Abstract Published clinical trials who studied the accuracy of patient-specific guides ( PSG ) for total knee arthroplasty exclude patients with articular deformity of the knee joint . We prospect ively analysed a series of 30 patients with post-traumatic osteoarthritis of the knee joint with use of PSG . At 1 year post-operative , the achieved biomechanical ( HKA ) axis and varus/valgus of the femur and tibia components were measured on anterior – posterior ( AP ) long-st and ing weight-bearing radiographs . Flexion/extension of the femoral and AP slope of the tibia component was measured on st and ard lateral radiographs . Percentages > 3 ° deviation of the pre-operative planned HKA axis and individual implant components were considered as outliers . Approved and used implant size , median blood loss ( ml ) and operation time ( min ) were obtained from the operation records . Pre- and 1-year post-operative patient-reported outcome measures ( PROMs ) were performed . Eighty-three per cent of the patients had a HKA axis restored <3 ° of the pre-operative planned alignment . Varus/valgus outliers were 0.0 and 6.7 % for the femoral and tibial components , respectively . Percentages of outliers of flexion/extension were 36.7 % for the femoral component and 10.0 % for the AP slope of the tibial component . Median blood loss was 300 ml ( 50–700 ) , while operation time was 67 min ( 44–144 ) . In 20 % of all cases , the approved implant size was changed into one size smaller . One-year post-operative PROMs improved significantly . We conclude that the accuracy of CT-based PSG is not impaired in patients with post-traumatic osteoarthritis and this modality can restore biomechanical limb alignment Summary Background Optimal positioning of implants and restoration of neutral mechanical axis are two primary surgical goals in total knee arthroplasty ( TKA ) . Despite modern instruments and improved surgical techniques , malalignment remains an important cause of early failure after TKA . The aim of this prospect i ve r and omized study was to compare the value of a new patient-matched instrument system ( PMI ) ( SignatureTM ; Biomet , Inc , Warsaw , Indiana ) to that of st and ard TKA surgical instrumentation ( STD ) in terms of coronal mechanical alignment , time of operation and blood loss . Patients and methods A total of 38 patients waiting for primary TKA were enrolled and r and omized into two groups ( 19 PMI and 19 STD ) . Magnetic resonance imaging was performed in all patients in the PMI group , and specific instruments for the femur and tibia were design ed preoperatively . All patients were operated on using the st and ard medial parapatellar approach with no use of tourniquet . Mechanical axis , time for the operation , and blood loss were evaluated . Results Patients in both groups had comparable age , body mass index , preoperative mechanical axis , Knee Society Score , and level of hemoglobin . Postoperative results showed that the PMI group fell significantly closer to neutral mechanical axis ( STD : 2.7 ± 1.7 , PMI : 1.7 ± 0.9 ; P = 0.013 ) with no outliers and a reduced time for the operation . There was no difference in the evaluation blood loss . Conclusions The use of PMI can contribute in achieving better mechanical axis with reduction in outliers and decreased operation time . Due to small differences between PMI and st and ard instruments , additional research are needed to confirm these preliminary results , and to discover potential benefits and functional improvements in the long-term outcome 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 
    Output:
    
agent
There were no significant differences regarding the biomechanical axis or frontal femoral and individual tibial component alignment .
Conclusion This systematic review and meta- analysis demonstrate that alignment with MRI-based PSI is at least as good as , if not better than , that with CT-based PSI .
***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 Long-leg radiographs ( LLR ) are often used in orthopaedics to assess limb alignment in patients undergoing total knee arthroplasty ( TKA ) . However , there are still concerns about the adequacy of measurements performed on LLR . We assessed the reliability and validity of measurements on LLR using three-dimensional computed tomography ( 3D CT)-scan as a gold st and ard . METHODS Six different surgeons measured the mechanical axis and position of the femoral and tibial components individually on 24 LLR .  Intraclass correlation coefficients ( ICC ) were calculated to obtain reliability and Bl and -Altman plots were constructed to assess agreement between measurements on LLR and measurements on 3D CT-scan . RESULTS ICC agreement for the six observer measurements on LLR was 0.70 for the femoral component and 0.80 for the tibial component . The mean difference between measurements performed on LLR and 3D CT-scan was 0.3 ° for the femoral component and -1.1 ° for the tibial component . Variation of the difference between LLR and 3D CT-scan for the femoral component was 1.1 ° and 0.9 ° for the tibial component . 95 % of the differences between measurements performed on LLR and 3D CT-scan were between -1.9 and 2.4 ° ( femoral component ) and between -2.9 and 0.7 ( tibial component ) . CONCLUSION Measurements on LLR show moderate to good reliability and , when compared to 3D CT-scan , show good validity . CLINICAL TRIAL REGISTRATION NUMBER institutional review board Atrium-Orbis-Zuyd , number : 11-T-15 . LEVEL OF EVIDENCE Prospect i ve cohort study , Level II 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 Patient-specific femoral and tibial cutting blocks produced with use of data from preoperative computed tomography ( CT ) or magnetic resonance imaging ( MRI ) scans have been employed recently to optimize component alignment in total knee arthroplasty . We report the results of a r and omized controlled trial in which CT scans were used to compare postoperative component alignment between patients treated with custom instruments  and those managed with traditional instruments . METHODS The in-hospital data and early clinical outcomes , including Knee Society scores , were determined in a r and omized clinical trial of forty-seven patients who had undergone a total of forty-eight primary total knee arthroplasties with patient-specific instruments ( twenty-two knees ) or st and ard instruments ( twenty-six knees ) . Orientation of the implants was compared by using three-dimensional CT data . RESULTS No significant differences were found between the study and control groups with respect to any clinical outcome after a minimum of six months of follow-up . The patient-specific tibial cutting block was ab and oned in favor of a st and ard external alignment jig in seven of the twenty-two study knees because of possible malalignment . A detailed analysis of intent-to-treat and per- protocol groups of study and control knees did not show any significant improvement in component alignment , including femoral component rotation in the axial plane , in the patients treated with the custom instruments . The percentage of outliers -- defined as less than -3 ° or more than 3 ° from the correct orientation of the tibial slope -- was significantly higher in the group treated with use of patient-specific blocks than it was in the control group , in both the intent-to-treat ( 32 % versus 8 % , p = 0.032 ) and the per- protocol ( 47 % versus 6 % , p = 0.0008 ) analysis . CONCLUSIONS There were no significant improvements in clinical outcomes or knee component alignment in patients treated with patient-specific cutting blocks as compared with those treated with st and ard instruments . The group treated with patient-specific cutting blocks had a significantly higher prevalence of malalignment in terms of tibial component slope than the knees treated with st and ard instruments Abstract Published clinical trials who studied the accuracy of patient-specific guides ( PSG ) for total knee arthroplasty exclude patients with articular deformity of the knee joint . We prospect ively analysed a series of 30 patients with post-traumatic osteoarthritis of the knee joint with use of PSG . At 1 year post-operative , the achieved biomechanical ( HKA ) axis and varus/valgus of the femur and tibia components were measured on anterior – posterior ( AP ) long-st and ing weight-bearing radiographs . Flexion/extension of the femoral and AP slope of the tibia component was measured on st and ard lateral radiographs . Percentages > 3 ° deviation of the pre-operative planned HKA axis and individual implant components were considered as outliers . Approved and used implant size , median blood loss ( ml ) and operation time ( min ) were obtained from the operation records . Pre- and 1-year post-operative patient-reported outcome measures ( PROMs ) were performed . Eighty-three per cent of the patients had a HKA axis restored <3 ° of the pre-operative planned alignment . Varus/valgus outliers were 0.0 and 6.7 % for the femoral and tibial components , respectively . Percentages of outliers of flexion/extension were 36.7 % for the femoral component and 10.0 % for the AP slope of the tibial component . Median blood loss was 300 ml ( 50–700 ) , while operation time was 67 min ( 44–144 ) . In 20 % of all cases , the approved implant size was changed into one size smaller . One-year post-operative PROMs improved significantly . We conclude that the accuracy of CT-based PSG is not impaired in patients with post-traumatic osteoarthritis and this modality can restore biomechanical limb alignment Summary Background Optimal positioning of implants and restoration of neutral mechanical axis are two primary surgical goals in total knee arthroplasty ( TKA ) . Despite modern instruments and improved surgical techniques , malalignment remains an important cause of early failure after TKA . The aim of this prospect i ve r and omized study was to compare the value of a new patient-matched instrument system ( PMI ) ( SignatureTM ; Biomet , Inc , Warsaw , Indiana ) to that of st and ard TKA surgical instrumentation ( STD ) in terms of coronal mechanical alignment , time of operation and blood loss . Patients and methods A total of 38 patients waiting for primary TKA were enrolled and r and omized into two groups ( 19 PMI and 19 STD ) . Magnetic resonance imaging was performed in all patients in the PMI group , and specific instruments for the femur and tibia were design ed preoperatively . All patients were operated on using the st and ard medial parapatellar approach with no use of tourniquet . Mechanical axis , time for the operation , and blood loss were evaluated . Results Patients in both groups had comparable age , body mass index , preoperative mechanical axis , Knee Society Score , and level of hemoglobin . Postoperative results showed that the PMI group fell significantly closer to neutral mechanical axis ( STD : 2.7 ± 1.7 , PMI : 1.7 ± 0.9 ; P = 0.013 ) with no outliers and a reduced time for the operation . There was no difference in the evaluation blood loss . Conclusions The use of PMI can contribute in achieving better mechanical axis with reduction in outliers and decreased operation time . Due to small differences between PMI and st and ard instruments , additional research are needed to confirm these preliminary results , and to discover potential benefits and functional improvements in the long-term outcome 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 
    Output:
    