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: The goal of this prospect i ve , r and omized , blinded trial was to determine if ligament balancing techniques for rotating platform TKA affect postoperative knee kinematics .  Sixteen patients with unilateral rotating platform TKA consented to participate in this institutional review board approved study . Eight patients were r and omly selected to receive ligament balancing with an instrumented joint spreader device and eight patients received ligament balancing using fixed thickness spacer blocks .  A single plane shape matching technique was used for kinematic analysis of static deep knee flexion and dynamic stair activities . There were no differences in knee kinematics between groups during static deep flexion activities . The spreader group demonstrated kinematics more similar to the normal knee during the ascending phase of the dynamic stair activity . Knee kinematics in static knee flexion were unaffected by ligament balancing technique , while knees balanced with the spreader demonstrated a medial pivot motion pattern during stair ascent . This medial pivot motion pattern may improve long-term results by more closely replicating normal knee kinematics Purpose Tibiofemoral contact kinematics or knee implant motions have a direct influence on patient function and implant longevity and should be evaluated for any new alignment technique such as kinematically aligned total knee arthroplasty ( TKA ) . Edge loading of the tibial liner and external rotation ( reverse of normal ) and adduction of the tibial component on the femoral component are undesirable contact kinematics that should be minimized . Accordingly , this study determined whether the overall prevalence of undesirable contact kinematics during st and ing , mid kneeling near 90 degrees and full kneeling with kinematically aligned TKA are minimal and not different between groups of consecutive patients treated by different surgeons . Methods Three surgeons were asked to perform cemented , kinematically aligned TKA with patient-specific guides in a consecutive series of patients with their preferred cruciate-retaining ( CR ) implant .  In vivo tibiofemoral contact positions were obtained using a 3- to 2-dimensional image registration technique in 69 subjects ( Vanguard CR – TKA N = 22 , and Triathlon CR – TKA N = 47 ) . Results Anterior or posterior edge loading of the tibial liner was not observed . The overall prevalence of external rotation of the tibial component on the femoral component of 6 % was low and not different between surgeons ( n.s . ) . The overall prevalence of adduction of the tibial component on the femoral component of 4 % was low and not different between surgeons ( n.s . ) . Conclusions Kinematically aligned TKA minimized the undesirable contact kinematics of edge loading of the tibial liner , and external rotation and adduction of the tibial component on the femoral component during st and ing and kneeling , which suggests an optimistic prognosis for durable long-term function . Level of evidence III Background Kneeling is one of the activities sought by patients after total knee arthroplasty ( TKA ) . This study investigated the six degrees of freedom ( DOF ) kinematics and three-dimensional ( 3D ) contact during weight-bearing kneeling . Methods A total of 16 South Korean female patients ( 22 knees ) after posteriorly stabilized ( PS ) TKA ( LPS-Flex ) were r and omly recruited and had the same surgeon . The patients were imaged using a dual fluoroscopic technique while they kneeled from initial to maximum flexion . The acquired images and 3D models were then used to recreate the in vivo pose of the components . Contact was determined by locating the surface intersections in the tibiofemoral and cam/post ( between the femoral cam and tibial post ) articular compartments . Results Patients flexed , on average , from 107.3 ° to 128.0 ° during the kneeling activity . Changes in kinematics included 1.0 mm of proximal , 0.9 mm of medial , and 7.6 mm of posterior translation and 1.7 ° of varus rotation ( P < 0.04 ) . A difference in internal tibial rotation was not detected . Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments , respectively . Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments . A decrease in articular contact was observed in both condyles , and lateral condylar lift-off increased with flexion ( P = 0.0001 ) . More than 80 % of the patients demonstrated cam/post engagement , which always occurred in the distal portion of the post . Conclusions In this patient cohort , the knee joint was constrained during the weight-bearing activity such that femoral subluxation and dislocation were not observed . Furthermore , posterior cam/post engagement occurred only in the distal portion of the tibial post , which may improve the longevity of the post . The tibiofemoral and cam/post articular contact data presented in this study further suggest that kneeling may be performed by patients after clinical ly successful PS TKA who feel comfortable with the activity and are free of pain BACKGROUND The reasons why surgeons prefer a particular  total knee replacement ( TKR )  to other viable options with lower cost or lower revision risk remain uncertain . This study examined the concept of surgeon 's preference in TKR ;  including the self-assigned utility of their preferred prosthesis , reasons to alter usual preference and barriers to permanently changing preference . METHODS Using a multinational electronic survey , 347 TKR performing orthopedic surgeons were studied using anonymous m and atory responses , mutually exclusive closed options , multiple responses blocking , automatic stem r and omization , Likert scale weighting , and an absence of neutral options . RESULTS The highest rated of the 17 attributes were " reproducibility of outcome , " " best functional outcome , " and " better kinematics . " The lowest rated were a " key-opinion leader or mentor uses it " and " new or innovative . " " Lowest revision risk " ranked 10th , with 19.9 % of surgeons stating it did not influence their preference . Cost did not influence 52.1 % of surgeons and 33.7 % agreed that their institution or system limited their preference . Surgeon 's demographics and preferred prosthesis or technique altered some attribute ratings including surgical volume , country of practice , type of preferred implant ; however , revision risk rating was not altered by any factor . Cost considerations altered rating of barriers to technique change . CONCLUSION Underst and ing why surgeons prefer certain TKR prostheses or techniques to other viable alternatives is vital to reduce unwarranted variation . This study suggests that the self-assigned reasons driving surgeon 's preferences , reasons for preference alteration , and barriers to change are multifactorial , diverse , and complex , with revision risk not being the highest rated attribute BACKGROUND Posterior-cruciate ligament retaining total knee arthroplasty design s have long been used with excellent clinical success , but often have shown kinematics and flexion performance that are significantly different from the natural knee . The purpose of this study was to compare deep-flexion knee kinematics in patients with two types of posterior-cruciate ligament retaining total knee arthroplasty .  METHODS One group received a traditional curved symmetric articular configuration , and one group received a design incorporating a lateral compartment which constrains the lateral condyle to the antero-posterior center of the tibial plateau in extension , but allows translation in flexion -- roughly approximating the role of the anterior cruciate ligament . In vivo kinematics were analyzed using three-dimensional model registration and plain radiographs of kneeling and squatting activities in 20 knees in 18 patients . FINDINGS Knees with the anterior cruciate ligament substituting design exhibited greater flexion , femoral antero-posterior translation and tibial internal rotation . INTERPRETATION Geometric features intended to improve knee flexion , including greater antero-posterior stability , a more posterior tibial sulcus , and reshaped femoral condyles , do provide measurable and significant differences in deep-flexion knee kinematics Patient expectations and their fulfilment are an important factor in determining patient-reported outcome and satisfaction of  hip ( THR ) and knee replacement ( TKR ) . The aim of this prospect i ve cohort study was to examine the expectations of patients undergoing THR and TKR  , and to identify differences in expectations , predictors of high expectations and the relationship between the fulfilment of expectations and patient-reported outcome measures . During the study period , patients who underwent 346 THRs and 323 TKRs  completed an expectation question naire , Oxford score  and  Short-Form 12 ( SF-12 ) score pre-operatively . At one year post-operatively , the Oxford score , SF-12 , patient satisfaction and expectation fulfilment were assessed . Univariable and multivariable analysis were performed . Improvements in mobility and daytime pain were the most important expectations in both groups . Expectation level did not differ between THR and TKR . Poor Oxford score , younger age and male gender significantly predicted high pre-operative expectations ( p < 0.001 ) . The level of pre-operative expectation was not significantly associated with the fulfilment of expectations or outcome . THR better met the expectations identified as important by patients . TKR failed to meet expectations of kneeling , squatting and stair climbing . High fulfilment of expectation in both THR and TKR was significantly predicted by young age , greater improvements in Oxford score and high pre-operative mental health scores . The fulfilment of expectations was highly correlated with satisfaction Background : Because of specific method ological difficulties in conducting r and omized trials , surgical research remains dependent predominantly on observational or non‐r and omized studies . Few vali date d instruments are available to determine the method ological quality of such studies either from the reader 's perspective or for the purpose of meta‐ analysis . The aim of the present study was to develop and vali date such an instrument BACKGROUND Articular geometry of knee implant has a competing impact on kinematics and contact mechanics of total knee arthroplasty ( TKA ) such that geometry with lower contact pressure will impose more constraints on knee kinematics . The geometric parameters that may cause this competing effect have not been well understood . This study aim ed to quantify the underlying relationships between implant geometry as input and its performance metrics as output . METHODS Parametric dimensions of a fixed-bearing cruciate retaining implant were  r and omized to generate a number of perturbed implant geometries . Performance metrics ( i.e. , maximum contact pressure , anterior-posterior range of motion [ A-P ROM ] and internal-external range of motion [ I-E ROM ] ) of each r and omized design were calculated using finite element analysis . The relative contributions of individual geometric variables to the performance metrics were then determined in terms of sensitivity indices ( SI ) . RESULTS The femoral and tibial distal or posterior radii and femoral frontal radius are the key parameters . In the sagittal plane , distal curvature of the femoral and tibial influenced both contact pressure , i.e. , SI=0.57 ; SI=0.65 , and A-P ROM , i.e. , SI=0.58 ; SI=0.6 , respectively . However , posterior curvature of the femoral and tibial implants had a smaller impact on the contact pressure , i.e. , SI=0.31 ; SI=0.23 and a higher impact on the I-E ROM , i.e. , SI=0.72 ; SI=0.58 . It is noteworthy that in the frontal plane , frontal radius of the femoral implant impacted both contact pressure ( SI=0.38 ) and I-E ROM ( SI=0.35 ) . CONCLUSION Findings of this study highlighted how changes in the conformity of the femoral and tibial can impact the performance metrics 
    Output:
    
agent
All design s demonstrated posterior – femoral translation and external rotation in kneeling , but posterior-stabilised design s were more posterior at maximal flexion when compared to cruciate retaining .
***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: The goal of this prospect i ve , r and omized , blinded trial was to determine if ligament balancing techniques for rotating platform TKA affect postoperative knee kinematics .  Sixteen patients with unilateral rotating platform TKA consented to participate in this institutional review board approved study . Eight patients were r and omly selected to receive ligament balancing with an instrumented joint spreader device and eight patients received ligament balancing using fixed thickness spacer blocks .  A single plane shape matching technique was used for kinematic analysis of static deep knee flexion and dynamic stair activities . There were no differences in knee kinematics between groups during static deep flexion activities . The spreader group demonstrated kinematics more similar to the normal knee during the ascending phase of the dynamic stair activity . Knee kinematics in static knee flexion were unaffected by ligament balancing technique , while knees balanced with the spreader demonstrated a medial pivot motion pattern during stair ascent . This medial pivot motion pattern may improve long-term results by more closely replicating normal knee kinematics Purpose Tibiofemoral contact kinematics or knee implant motions have a direct influence on patient function and implant longevity and should be evaluated for any new alignment technique such as kinematically aligned total knee arthroplasty ( TKA ) . Edge loading of the tibial liner and external rotation ( reverse of normal ) and adduction of the tibial component on the femoral component are undesirable contact kinematics that should be minimized . Accordingly , this study determined whether the overall prevalence of undesirable contact kinematics during st and ing , mid kneeling near 90 degrees and full kneeling with kinematically aligned TKA are minimal and not different between groups of consecutive patients treated by different surgeons . Methods Three surgeons were asked to perform cemented , kinematically aligned TKA with patient-specific guides in a consecutive series of patients with their preferred cruciate-retaining ( CR ) implant .  In vivo tibiofemoral contact positions were obtained using a 3- to 2-dimensional image registration technique in 69 subjects ( Vanguard CR – TKA N = 22 , and Triathlon CR – TKA N = 47 ) . Results Anterior or posterior edge loading of the tibial liner was not observed . The overall prevalence of external rotation of the tibial component on the femoral component of 6 % was low and not different between surgeons ( n.s . ) . The overall prevalence of adduction of the tibial component on the femoral component of 4 % was low and not different between surgeons ( n.s . ) . Conclusions Kinematically aligned TKA minimized the undesirable contact kinematics of edge loading of the tibial liner , and external rotation and adduction of the tibial component on the femoral component during st and ing and kneeling , which suggests an optimistic prognosis for durable long-term function . Level of evidence III Background Kneeling is one of the activities sought by patients after total knee arthroplasty ( TKA ) . This study investigated the six degrees of freedom ( DOF ) kinematics and three-dimensional ( 3D ) contact during weight-bearing kneeling . Methods A total of 16 South Korean female patients ( 22 knees ) after posteriorly stabilized ( PS ) TKA ( LPS-Flex ) were r and omly recruited and had the same surgeon . The patients were imaged using a dual fluoroscopic technique while they kneeled from initial to maximum flexion . The acquired images and 3D models were then used to recreate the in vivo pose of the components . Contact was determined by locating the surface intersections in the tibiofemoral and cam/post ( between the femoral cam and tibial post ) articular compartments . Results Patients flexed , on average , from 107.3 ° to 128.0 ° during the kneeling activity . Changes in kinematics included 1.0 mm of proximal , 0.9 mm of medial , and 7.6 mm of posterior translation and 1.7 ° of varus rotation ( P < 0.04 ) . A difference in internal tibial rotation was not detected . Articular contact moved posteriorly by 5.9 mm and 6.4 mm in the medial and lateral compartments , respectively . Contact also moved medially by 3.2 mm and 5.8 mm in the medial and lateral compartments . A decrease in articular contact was observed in both condyles , and lateral condylar lift-off increased with flexion ( P = 0.0001 ) . More than 80 % of the patients demonstrated cam/post engagement , which always occurred in the distal portion of the post . Conclusions In this patient cohort , the knee joint was constrained during the weight-bearing activity such that femoral subluxation and dislocation were not observed . Furthermore , posterior cam/post engagement occurred only in the distal portion of the tibial post , which may improve the longevity of the post . The tibiofemoral and cam/post articular contact data presented in this study further suggest that kneeling may be performed by patients after clinical ly successful PS TKA who feel comfortable with the activity and are free of pain BACKGROUND The reasons why surgeons prefer a particular  total knee replacement ( TKR )  to other viable options with lower cost or lower revision risk remain uncertain . This study examined the concept of surgeon 's preference in TKR ;  including the self-assigned utility of their preferred prosthesis , reasons to alter usual preference and barriers to permanently changing preference . METHODS Using a multinational electronic survey , 347 TKR performing orthopedic surgeons were studied using anonymous m and atory responses , mutually exclusive closed options , multiple responses blocking , automatic stem r and omization , Likert scale weighting , and an absence of neutral options . RESULTS The highest rated of the 17 attributes were " reproducibility of outcome , " " best functional outcome , " and " better kinematics . " The lowest rated were a " key-opinion leader or mentor uses it " and " new or innovative . " " Lowest revision risk " ranked 10th , with 19.9 % of surgeons stating it did not influence their preference . Cost did not influence 52.1 % of surgeons and 33.7 % agreed that their institution or system limited their preference . Surgeon 's demographics and preferred prosthesis or technique altered some attribute ratings including surgical volume , country of practice , type of preferred implant ; however , revision risk rating was not altered by any factor . Cost considerations altered rating of barriers to technique change . CONCLUSION Underst and ing why surgeons prefer certain TKR prostheses or techniques to other viable alternatives is vital to reduce unwarranted variation . This study suggests that the self-assigned reasons driving surgeon 's preferences , reasons for preference alteration , and barriers to change are multifactorial , diverse , and complex , with revision risk not being the highest rated attribute BACKGROUND Posterior-cruciate ligament retaining total knee arthroplasty design s have long been used with excellent clinical success , but often have shown kinematics and flexion performance that are significantly different from the natural knee . The purpose of this study was to compare deep-flexion knee kinematics in patients with two types of posterior-cruciate ligament retaining total knee arthroplasty .  METHODS One group received a traditional curved symmetric articular configuration , and one group received a design incorporating a lateral compartment which constrains the lateral condyle to the antero-posterior center of the tibial plateau in extension , but allows translation in flexion -- roughly approximating the role of the anterior cruciate ligament . In vivo kinematics were analyzed using three-dimensional model registration and plain radiographs of kneeling and squatting activities in 20 knees in 18 patients . FINDINGS Knees with the anterior cruciate ligament substituting design exhibited greater flexion , femoral antero-posterior translation and tibial internal rotation . INTERPRETATION Geometric features intended to improve knee flexion , including greater antero-posterior stability , a more posterior tibial sulcus , and reshaped femoral condyles , do provide measurable and significant differences in deep-flexion knee kinematics Patient expectations and their fulfilment are an important factor in determining patient-reported outcome and satisfaction of  hip ( THR ) and knee replacement ( TKR ) . The aim of this prospect i ve cohort study was to examine the expectations of patients undergoing THR and TKR  , and to identify differences in expectations , predictors of high expectations and the relationship between the fulfilment of expectations and patient-reported outcome measures . During the study period , patients who underwent 346 THRs and 323 TKRs  completed an expectation question naire , Oxford score  and  Short-Form 12 ( SF-12 ) score pre-operatively . At one year post-operatively , the Oxford score , SF-12 , patient satisfaction and expectation fulfilment were assessed . Univariable and multivariable analysis were performed . Improvements in mobility and daytime pain were the most important expectations in both groups . Expectation level did not differ between THR and TKR . Poor Oxford score , younger age and male gender significantly predicted high pre-operative expectations ( p < 0.001 ) . The level of pre-operative expectation was not significantly associated with the fulfilment of expectations or outcome . THR better met the expectations identified as important by patients . TKR failed to meet expectations of kneeling , squatting and stair climbing . High fulfilment of expectation in both THR and TKR was significantly predicted by young age , greater improvements in Oxford score and high pre-operative mental health scores . The fulfilment of expectations was highly correlated with satisfaction Background : Because of specific method ological difficulties in conducting r and omized trials , surgical research remains dependent predominantly on observational or non‐r and omized studies . Few vali date d instruments are available to determine the method ological quality of such studies either from the reader 's perspective or for the purpose of meta‐ analysis . The aim of the present study was to develop and vali date such an instrument BACKGROUND Articular geometry of knee implant has a competing impact on kinematics and contact mechanics of total knee arthroplasty ( TKA ) such that geometry with lower contact pressure will impose more constraints on knee kinematics . The geometric parameters that may cause this competing effect have not been well understood . This study aim ed to quantify the underlying relationships between implant geometry as input and its performance metrics as output . METHODS Parametric dimensions of a fixed-bearing cruciate retaining implant were  r and omized to generate a number of perturbed implant geometries . Performance metrics ( i.e. , maximum contact pressure , anterior-posterior range of motion [ A-P ROM ] and internal-external range of motion [ I-E ROM ] ) of each r and omized design were calculated using finite element analysis . The relative contributions of individual geometric variables to the performance metrics were then determined in terms of sensitivity indices ( SI ) . RESULTS The femoral and tibial distal or posterior radii and femoral frontal radius are the key parameters . In the sagittal plane , distal curvature of the femoral and tibial influenced both contact pressure , i.e. , SI=0.57 ; SI=0.65 , and A-P ROM , i.e. , SI=0.58 ; SI=0.6 , respectively . However , posterior curvature of the femoral and tibial implants had a smaller impact on the contact pressure , i.e. , SI=0.31 ; SI=0.23 and a higher impact on the I-E ROM , i.e. , SI=0.72 ; SI=0.58 . It is noteworthy that in the frontal plane , frontal radius of the femoral implant impacted both contact pressure ( SI=0.38 ) and I-E ROM ( SI=0.35 ) . CONCLUSION Findings of this study highlighted how changes in the conformity of the femoral and tibial can impact the performance metrics 
    Output:
    