***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: We carried out a prospect i ve , continuous study on 529 patients who underwent primary total knee replacement between January 2006 and December 2007 at a major teaching hospital . The aim was to investigate weight change and the functional and clinical outcome in non-obese and obese groups at 12 months post-operatively . The patients were grouped according to their pre-operative body mass index ( BMI ) as follows : non-obese ( BMI < 30 kg/m(2 ) ) , obese ( BMI ( 3 ) 30 to 39 kg/m(2 ) ) and morbidly obese ( BMI > 40 kg/m(2 ) ) . The clinical outcome data were available for all patients and functional outcome data for 521 ( 98.5 % ) . Overall , 318 ( 60.1 % ) of the patients were obese or morbidly obese . At 12 months , a clinical ly significant weight loss of > or = 5 % had occurred in 40 ( 12.6 % ) of the obese patients , but 107 ( 21 % ) gained weight . The change in the International Knee Society score was less in obese and morbidly obese compared with non-obese patients ( p = 0.016 ) . Adverse events occurred in 30 ( 14.2 % ) of the non-obese , 59 ( 22.6 % ) of the obese and 20 ( 35.1 % ) of the morbidly obese patients ( p = 0.001 ) BACKGROUND Limited previous findings have detailed biomechanical advantages following implantation with mobile bearing ( MB ) prostheses after total knee replacement ( TKR ) surgery during walking . The aim of this study was to compare three dimensional spatiotemporal , kinematic , and kinetic parameters during walking to examine whether MBs offer functional advantages over fixed bearing ( FB ) design s. METHODS Sixteen patients undergoing primary unilateral TKR surgery were r and omised to receive either a FB ( n=8 ) or MB ( n=8 ) total knee prosthesis .  Eight age and gender matched controls underwent the same protocol on one occasion . A 12 camera Vicon system integrated with four force plates was used . Patients were tested pre-surgery and nine months post-surgery . RESULTS No significant differences between FB and MB groups were found at any time point in the spatiotemporal parameters . The MB group was found to have a significantly reduced frontal plane knee range of motion ( ROM ) at pre-surgery than the FB group ( FB=14.92±4.02 ° ; MB=8.87±4.82 ° ) , with the difference not observed post-surgery . No further significant kinematic or kinetic differences were observed between FB and MB groups . Fixed bearing and MB groups both displayed spatiotemporal , kinematic , and kinetic differences when compared to controls . Fixed bearing and MB groups differed from controls in six and five parameters at nine months post-surgery , respectively . CONCLUSIONS No functional advantages were found in knees implanted with MB prostheses during walking , with both groups indicative of similar differences when compared to normal knee biomechanics following prosthesis implantation . LEVEL OF EVIDENCE Level II Purpose The theoretical superiority of mobile-bearing total knee arthroplasties ( TKAs ) has not yet been proven in clinical studies . The aim of the current study was to compare and to analyse in a patient population that had received either a fixed or a mobile TKA differences in gait analysis electromyography and clinical scores . Methods In a prospect i ve , r and omized , patient- and observer-blinded clinical study , 33 patients with primary osteoarthritis of the knee were included . All patients received a Genesis II total knee replacement . Sixteen patients received a mobile  and 17 a  fixed-bearing cruciate retaining Genesis II TKA .  Clinical and quality -of-life scores , electromyography and gait analysis were applied preoperatively and postoperatively with a follow-up of 24 months . Results In both groups , improvements from pre- to postoperative were detected . whereas the results of gait analysis and electromyography did not show any differences . The results from the clinical and the quality -of-life scores improved from pre- to postoperative , while the Knee Society Score showed a superiority of the mobile-bearing group ( mean 159 ± 28 ) over the fixed-bearing group ( mean 134 ± 41 ) . Conclusion No functional advantage of mobile over fixed-bearing TKA was detected , although the mobile-bearing group had better clinical results for which a reason could not be found . These results only apply to cruciate retaining mobile-bearing TKA with a bearing which allows both rotation and anteroposterior translation . Level of evidence Prospect i ve comparative study , Level II OBJECTIVE : To test the feasibility of creating a valid and reliable checklist with the following features : appropriate for assessing both r and omised and non-r and omised studies ; provision of both an overall score for study quality and a profile of scores not only for the quality of reporting , internal validity ( bias and confounding ) and power , but also for external validity . DESIGN : A pilot version was first developed , based on epidemiological principles , review s , and existing checklists for r and omised studies . Face and content validity were assessed by three experienced review ers and reliability was determined using two raters assessing 10 r and omised and 10 non-r and omised studies . Using different raters , the checklist was revised and tested for internal consistency ( Kuder-Richardson 20 ) , test-retest and inter-rater reliability ( Spearman correlation coefficient and sign rank test ; kappa statistics ) , criterion validity , and respondent burden . MAIN RESULTS : The performance of the checklist improved considerably after revision of a pilot version . The Quality Index had high internal consistency ( KR-20 : 0.89 ) as did the subscales apart from external validity ( KR-20 : 0.54 ) . Test-retest ( r 0.88 ) and inter-rater ( r 0.75 ) reliability of the Quality Index were good . Reliability of the subscales varied from good ( bias ) to poor ( external validity ) . The Quality Index correlated highly with an existing , established instrument for assessing r and omised studies ( r 0.90 ) . There was little difference between its performance with non-r and omised and with r and omised studies . Raters took about 20 minutes to assess each paper ( range 10 to 45 minutes ) . CONCLUSIONS : This study has shown that it is feasible to develop a checklist that can be used to assess the method ological quality not only of r and omised controlled trials but also non-r and omised studies . It has also shown that it is possible to produce a checklist that provides a profile of the paper , alerting review ers to its particular method ological strengths and weaknesses . Further work is required to improve the checklist and the training of raters in the assessment of external validity Although treatments for osteoarthritis of the knee are often directed at relieving pain , pain may cause patients to alter how they perform activities to decrease the loads on the joints . The knee-adduction moment is a major determinant of the load distribution between the medial and lateral plateaus . Therefore , the interrelationship between pain and the external knee-adduction moment during walking may be especially important for underst and ing mechanical factors related to the progression of medial tibiofemoral osteoarthritis . Fifty-three subjects with symptomatic radiographic evidence of osteoarthritis of the knee were studied . These subjects were a subset of those enrolled in a double-blind study in which  gait analysis and radiographic and clinical evaluations were performed after a 2-week washout of anti-inflammatory and analgesic treatment . The subjects then took a nonsteroidal anti-inflammatory drug , acetaminophen , or placebo for 2 weeks , and the gait and clinical evaluations were repeated . The change in the peak external adduction moment between the two evaluations was inversely correlated with the change in pain ( R = 0.48 , p < 0.001 ) and was significantly different between those whose pain increased ( n = 7 ) , decreased ( n = 18 ) , or remained unchanged ( n = 28 ) ( p = 0.009 ) . Those with increased pain had a significant decrease in the peak external adduction ( p = 0.005 ) and flexion moments ( p = 0.023 ) . In contrast , the subjects with decreased pain tended to have an increase in the peak external adduction moment ( p = 0.095 ) and had a significant increase in the peak external extension moment ( p = 0.017 ) . The subjects whose pain was unchanged had no significant change in the peak external adduction ( p = 0.757 ) , flexion ( p = 0.234 ) , or extension ( p = 0.465 ) moments . Thus , decreases in pain among patients with medial tibiofemoral osteoarthritis were related to increased loading of the degenerative portion of the joints . Additional long-term prospect i ve studies are needed to determine whether increased loading during walking actually results in accelerated progression of the disease BACKGROUND Little is known about the effects of total knee replacement surgery on the contributions of individual joint moments to the total support moment . A better underst and ing of these effects may enhance rehabilitation protocol s and determine factors related to long-term surgical outcome . METHOD Twenty-one subjects with total knee replacement and 21 controls performed level walking and stair ascent  at two testing periods , pre- and 6 months post-surgery . Variables studied included gait velocity , stride length , knee flexion angle , net joint moments of the hip , knee and ankle , and total support moment . Data were analyzed at the first peak vertical ground reaction force . FINDINGS For level walking , the total support moment , knee extensor moment , and knee flexion angle of total knee replacement patients were less than controls at post-surgery . For stair ascent , the patient group total support moment , ankle plantarflexor moment , and knee flexion angle were less than controls at both testing periods , while knee extensor moment was less than controls at post-surgery . Extensor synergies of the total knee replacement patients revealed less knee and more hip contributions during level walking and larger hip contributions during stair ascent to the total support moment than controls at both testing periods . INTERPRETATION A feature of total knee replacement gait , pre- and post-surgery , is a stiff knee attitude which may serve to protect the quadriceps . The larger hip extensor contribution to the total support moment observed in the patients may compensate for the diminished knee extensor contribution during level walking and stair ascent We report a prospect i ve study of gait and tibial component migration  in 45 patients with osteoarthritis treated by total knee arthroplasty ( TKA ) .  Migration  was measured over two years using roentgen stereophotogrammetry . We used the previously established threshold of 200 microm migration in the second postoperative year to distinguish two groups : a risk group of 15 patients and a stable group of 28 patients . We performed  gait analysis before operation and at six months and at two years after TKA . On all three occasions we found significant differences between the two groups in the mean sagittal plane moments of the knee joint . The risk group walked with higher peak flexion moments than the stable group . The two groups were not discriminated by any clinical or radiological criteria or other gait characteristics . The relationship which we have found between gait with increased flexion moments and risk of tibial component loosening warrants further study as regards the aetiology of prosthetic loosening and possible methods of influencing its incidence Background Although some clinical reports suggest patient-specific instrumentation in TKA may improve alignment , reduce surgical time , and lower hospital costs , it is unknown whether it improves pain- and function-related outcomes and gait . Questions / purpose sWe hypothesized that TKA performed with patient-specific instrumentation would improve patient-reported outcomes measured by vali date d scoring tools and level gait as ascertained with three-dimensional ( 3-D ) analysis compared with conventional instrumentation 3 months after surgery . Methods We r and omized 40 patients into two groups using either patient-specific instrumentation or conventional instrumentation .  Patients were evaluated preoperatively and 3 months after surgery . Assessment tools included subjective functional outcome and quality -of-life ( QOL ) scores using vali date d question naires ( New Knee Society Score © [ KSS ] , Knee Injury and Osteoarthritis Outcome Score [ KOOS ] , and SF-12 ) . In addition , gait analysis was evaluated with a 3-D system during level walking . The study was powered a priori at 90 % to detect a difference in walking speed of 0.1 m/second , which was considered a clinical ly important difference , and in a post hoc analysis at 80 % to detect a difference of 10 points in KSS . Results There were improvements from preoperatively to 3 months postoperatively in functional scores , QOL , and knee kinematic and kinetic gait parameters during level walking . However , there was no difference between the patient-specific instrumentation and conventional instrumentation groups in KSS , KOOS , SF-12 , or 3-D gait parameters . Conclusions Our observations suggest that patient-specific instrumentation does not confer a substantial advantage in early functional or gait outcomes after TKA . It is possible that differences may emerge , and this study does not allow one to predict any additional variances in the intermediate followup period from 6 months to 1 year postoperatively . However , the goals of the study were to investigate the recovery period as early pain and functional outcomes are becoming increasingly important to patients and surgeons . Level of Evidence Level I , therapeutic study . See the Instructions to Authors for a complete description of levels of evidence Background While some clinical reports suggest minimally invasive surgical ( MIS ) techniques improve recovery and reduce pain in the first months after TKA , it is unclear whether it improves gait and thigh muscle strength . Questions / Purpose sWe hypothesized TKA performed through a mini-subvastus approach would 
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FINDINGS Following KA , in the frontal plane , the maximum knee adduction angle and external knee adduction moment ( KAM ) tended to decrease .
In the sagittal plane , findings suggest that the maximum knee flexion moment is increased .
INTERPRETATION Overall , it appears that KA results in a decreased peak KAM and maximum knee adduction angles , an increased peak knee flexion moment and inconsistent changes in the peak knee flexion angle .