***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 The additional effect of anterior cruciate ligament ( ACL ) reconstruction on muscle strength and physical performance after a structured exercise programme is not well understood . Objectives To investigate and compare muscle strength and physical performance test results after a structured exercise programme , in young active adults with acute ACL injury , between those treated with and without ACL reconstruction ( ACLR )  and to evaluate these test results as predictors of clinical outcomes 2 and 5 years after injury . Study design Prospect i ve cohort study . Methods In a treatment r and omised controlled trial of acute ACL injury ( the KANON- study ) , 87/121 young active adults underwent two muscle strength tests and five physical performance tests after a structured exercise programme ( median 37 ( IQR 24 ) weeks after injury ) . Results were presented and compared as limb symmetry indices ( LSI ) ; endpoints in predictive analyses were having a delayed ACLR over the first 5 years and self-reported knee function ( Knee injury and Osteoarthritis Outcome Score ; KOOS4 ) at 2 and 5 years . Results Overall , 74–95 % of patients had LSI≥90 % in the individual tests , with no difference between treatment groups ( p=0.08–0.92 ) . Results of the one-leg rise tests predicted KOOS4 at 2 and 5 years ( R2=0.25 and 0.24 , p=0.001 and 0.002 ) and vertical hop results predicted having a delayed ACLR over a 5-year course after injury ( p=0.048 ) in those starting with exercise alone ( n=21 ) . Conclusions After an acute ACL tear , the majority of young active adults regain physical performance and muscle strength  after a structured exercise programme , with or without surgical reconstruction . Poor physical performance at the end of rehabilitation predicted worse patient-reported outcomes at 2 and 5 years regardless of treatment . Registration number : IS RCT N84752559 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 Purpose Several studies compare the short- and long-term results of anterior cruciate ligament ( ACL ) reconstruction using bone-patellar tendon-bone ( BPTB ) graft or double-looped semitendinosus and gracilis ( DLSG ) graft . However , no studies evaluate the long-term results of BPTB grafts fixed with metal interference screws and DLSG grafts fixed with the Bone Mulch Screw and the Washer Loc . This prospect i ve r and omized multicentre study has the null hypothesis that there is no difference in long-term outcome between the two procedures . Methods A total of 114 patients with a symptomatic ACL rupture were r and omized to reconstruction with either a BPTB graft ( N = 58 ) or a DLSG graft ( N = 56 ) . Follow-up was conducted after one , two and seven years . At the seven-year follow-up , 102 of the 114 patients ( 89 % ) were available for evaluation ; however , 16 of these by telephone-interview only . Results Ten patients in the BPTB group and 19 patients in the DLSG group underwent additional knee surgery ( P = 0.048 ) , two and three , respectively , of these were ACL revisions ( n.s . ) . The total flexion work was lower in the DLSG group ( P = 0.001 ) . The mean peak flexion torque and extension work , however , showed no difference between the groups . No significant differences were found between the groups regarding the Tegner activity score , the Lysholm functional score , the Knee injury and osteoarthritis outcome score ( KOOS ) , subjective knee function , anterior knee pain or mobility . There was no significant difference in laxity between the groups on the Lachman test or the KT-1,000 maximum manual force test . Conclusions Both grafts and fixation methods result ed in satisfactory subjective outcome and objective stability . Both these methods can therefore be considered as suitable alternatives for ACL reconstructions . Level of evidence II We investigated the long-term outcome of 100 patients 15 years after having been r and omly allocated to primary repair ( augmented or non-augmented ) or non-surgical treatment of an anterior cruciate ligament ( ACL ) rupture . The subjective outcome was similar between the groups , with no difference regarding activity level and knee-injury and osteoarthritis outcome score but with a slightly lower Lysholm score for the non-surgically treated group . This difference was attributed to more instability symptoms . The radiological osteoarthritis ( OA ) frequency did not differ between surgically or non-surgically treated patients , but if a meniscectomy was performed , two-thirds of the patients showed OA changes regardless of initial treatment of the ACL . There were significantly more meniscus injuries in patients initially treated non-surgically . One-third of the patients in the non-surgically treated group underwent  secondary ACL reconstruction  due to instability problems . In this study , ACL repair itself could not reduce the risk of OA nor increase the subjective outcome scores . However , one-third of the non-surgical treated patients were later ACL reconstructed due to instability . The status of the menisci was found to be the most important predictor of developing OA . Early ACL repair and also ACL reconstruction can reduce the risk of secondary meniscus tears . Indirectly this supports the hypothesis that early stabilization of the knee after ACL injury is advantageous for the long-term outcome Background There are conflicting results in the literature regarding the association between radiographic knee osteoarthritis ( OA ) and symptoms and function in subjects with previous anterior cruciate ligament ( ACL ) reconstruction . Aim To investigate the associations between radiographic tibiofemoral knee OA and knee pain , symptoms , function and knee-related quality of life ( QOL ) 10–15 years after ACL reconstruction . Study design Cross-sectional study . Material and methods 258 subjects were consecutively included at the time of ACL reconstruction and followed up prospect ively . The authors included the Knee Injury and Osteoarthritis Outcome Score to evaluate knee pain , other symptoms ( symptoms ) , activities of daily living and sport and recreation ( Sport/Rec ) and QOL . The subjects underwent st and ing radiographs 10–15 years after the ACL reconstruction . The radiographs were grade d with the Kellgren and Lawrence ( K&L ) classification ( grade 0–4 ) . Results 210 subjects ( 81 % ) consented to participate in the 10–15-year follow-up . Radiographic knee OA ( K&L ≥ grade 2 ) was detected in 71 % , and 24 % showed moderate or severe radiographic knee OA ( K&L grade s 3 and 4 ) . No significant associations were detected between radiographic knee OA ( K&L grade ≥2 ) and pain , function or QOL , respectively , but subjects with radiographic knee OA showed significantly increased symptoms . Severe radiographic knee OA ( K&L grade 4 ) was significantly associated with more pain , symptoms , impaired Sport/Rec and reduced QOL . Conclusion Subjects with radiographic knee OA showed significantly more symptoms than those without OA , and subjects with severe radiographic knee OA had significantly more pain , impaired function and reduced quality of life than those without radiographic knee OA 10–15 years after ACL reconstruction Background Specific guidelines for operative versus nonoperative management of anterior cruciate ligament injuries do not yet exist . Hypothesis Surgical risk factors can be used to indicate whether reconstruction or conservative management is best for an individual patient . Study Design Prospect i ve nonr and omized controlled clinical trial ; Level of evidence , 2 . Methods Patients were classified as high , moderate , or low risk using preinjury sports participation and knee laxity measurements .  Early anterior cruciate ligament reconstruction ( within 3 months of injury ) was recommended to high-risk patients and conservative care to low-risk patients . It was recommended that moderate-risk patients have either early reconstruction or conservative care , according to the day of presentation . Assessment of subjective outcomes , activity , physical measurements , and radiographs was performed at mean follow-up of 6.6 years . Results Early phase conservative management result ed in more late phase meniscus surgery than did early phase reconstruction at all risk levels ( high risk , 25 % vs 6.5 % ; moderate risk , 37 % vs 7.7 % , P = . 01 ; low risk , 16 % vs 0 % ) . Early- and late-reconstruction patients ’ Tegner scores increased from presurgery to follow-up ( P < . 001 ) but did not return to preinjury levels . Early-reconstruction patients had higher rates of degenerative change on radiographs than did nonreconstruction patients ( P < . 05 ) . Conclusions Early phase reconstruction reduced late phase knee laxity , risk of symptomatic instability , and the risk of late meniscus tear and surgery .  Moderate- and high-risk patients had similar rates of late phase injury and surgery . Reconstruction did not prevent the appearance of late degenerative changes on radiographs . Relationship between bone contusion on initial magnetic resonance images and the finding of degenerative changes on follow-up radiographs were not detected . The treatment algorithm used in this study was effective in predicting risk of late phase knee surgery Background Anterior cruciate ligament injuries are common in athletes , but there are few studies of long-term outcomes . Hypothesis Long-term knee function of anterior cruciate ligament-injured athletes is inferior to that of their uninjured teammates . Study Design Retrospective cohort study . Methods Thirty-three Division I-A athletes who had sustained an anterior cruciate ligament injury during their college career completed a series of question naires that assessed knee function and quality of life 2 to 14 years after injury . Their responses were compared with those of a matched cohort of their uninjured teammates . Results There were no differences in the mean Tegner scores , modified Lysholm scores , or in the scores of the SF-36 between groups . Sixteen anterior cruciate ligament-injured athletes scored A or B in the subjective portion of the International Knee Documentation Committee score and 17 scored C or D , whereas 24 control subjects scored A or B and 9 scored C or D , a statistically significant difference between groups . Five injured and 14 control athletes had participated at a professional or national team level after college . Conclusions Quality of life of elite collegiate athletes who sustained an anterior cruciate ligament injury was not significantly different from that of their uninjured teammates , but knee function differed between groups PURPOSE The purpose of the study was to quantify the amount of agreement among orthopaedic surgeons regarding the natural history of the anterior cruciate ligament (ACL)-deficient knee , surgery , and rehabilitation , and the treatment of these patients . TYPE OF STUDY Physician mail survey . METHODS Orthopaedic surgeons were r and omly selected from the American Academy of Orthopaedic Surgeons ( AAOS ) directory . Only individuals who treated or referred ACL-insufficient patients for treatment within the past year were asked to complete the 3-page survey . The survey included 25 questions regarding clinical opinion . Clinical agreement was present when 80 % or more of the surgeons agreed on the same response option . RESULTS The total number of surgeons who responded to the survey was 397 ( response rate , 54.8 % ) and the number who had treated or referred ACL-insufficient patients in the past year was 261 . Among surgeons who completed the question naire , the response rates to the individual questions ranged from 92 % to 100 % . The mean response rate for all questions was 97.4 % . The mean age of the surgeons was 48.4 years , and 35.8 % considered their practice to be a subspecialty in sports medicine or knee surgery . For 
    Output:
    
This systematic review found impaired knee-related QOL in ACL-deficient individuals ≥5 years after ACL rupture , compared to population norms .
Meta- analysis revealed similar knee-related QOL in ACL-deficient and ACL-reconstructed groups , and no difference in health-related QOL scores for seven of the eight SF-36 domains