***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 To evaluate muscle torque , lower extremity coordination , and knee laxity after ACL reconstruction comparing patients operated on with semitendinosus graft ( ST ) and patients with combined semitendinosus and gracilis ( STGR ) grafts .  Methods Forty-six subjects who underwent ST ( n = 23 ) or STGR harvest ( n = 23 ) ACL reconstruction participated in this study . Quadriceps and hamstring torque were recorded using an isokinetic dynamometer . The  anterior tibial translation  was measured using the Kneelax 3 Arthrometer . The eccentric and concentric motor coordination was tested by multi-joint lower-limb tracking-trajectory test . All measurements were taken 12 months after surgery . Side-to-side differences were determined for all subjects . Results Side-to-side differences in extensor peak torque at 180 ° /s and 60 ° /s did not differ between semitendinosus ( ST ) and semitendinosus + gracilis ( STGR ) groups ( n.s . ) . However , side-to-side differences in flexor peak torque were significantly higher at 60 ° /s for the STGR group than the ST group ( P = 0.002 ) . Side-to-side differences in eccentric and concentric parts of tracking-trajectory test and anterior tibial translation did not differ between the STGR and the ST groups ( n.s . ) . Conclusion The outcomes of this study suggested that additional harvest of gracilis did not influence lower extremity motor control , quadriceps muscle torque , and anterior tibial translation ; however , it affected knee flexion isokinetic torque negatively at low angular velocity . This finding could be important for functional activity or sports with high dem and s on hamstring muscle strength . It is recommended that gracilis muscle should be preserved as possible during ACL reconstruction . Level of evidence Prospect i ve comparative study , Level II Purpose The purpose of this prospect i ve study was to describe the variability in leg muscle power and hop performance up to 2 years among patients following ACL reconstruction and specifically to illustrate the effects of various criteria for an acceptable level of muscle function . Methods Eighty-two patients ( 56 men and 26 women ) with a mean age of 28 years , who underwent ACL reconstruction using either hamstring tendons ( n = 46 ) or a patellar tendon ( n = 36 ) , were assessed pre-operatively and 3 , 6 , 12 and 24 months  post-surgery  with a battery of three lower extremity muscle power tests and a battery of three hop tests . Results Leg symmetry index ( LSI ) values at group level ranged between 73 and 100 % at all follow-ups . When the tests were evaluated individually , patients reached an average LSI of ≥90 % at 24 months . The success rate at 24 months for the muscle power test battery , that is , patients with an LSI of ≥90 % in all three tests , was 48 and 44 % for the hop test battery . The success rate at 24 months for both test batteries on all six muscle function tests was 22 % . The criterion of an LSI of ≥80 % result ed in 53 % of the patients having an acceptable level on all six tests , while with a criterion of an LSI of ≥100 % , none of the patients reached an acceptable level . Conclusion At group level and in single muscle function tests , the muscle function outcome 1 and 2 years after ACL reconstruction is satisfactory in the present study and on a par with the results presented in the literature . However , when using more dem and ing criteria for a successful muscle function outcome , using batteries of tests or increasing the acceptable LSI level from ≥90 % to ≥95 % or ≥100 % , the results are considered to be poor . It is suggested that this should be taken into consideration when presenting results after ACL rehabilitation , deciding on the criteria for a safe return to sports , or design ing rehabilitation programmes after ACL reconstruction . Level of evidence Prognostic prospect i ve cohort study , Level BACKGROUND The diagnosis of clinical ly important meniscal tears of the knee remains challenging , and it is unknown why only some injuries become painful . The role of inflammatory cytokines in generating pain following meniscal injury remains unclear . This study aim ed to investigate the cytokine profile in patients with acute knee pain believed to be secondary to meniscal damage . METHODS This prospect i ve cohort study included thirty-two patients without rheumatoid arthritis who had knee pain for less than six months , with either an acute or insidious onset , and elected to have arthroscopic treatment after nonoperative management had failed . Twenty-three of these patients elected to have the contralateral , nonoperatively treated knee lavaged at the time of arthroscopy .  Fifteen asymptomatic control subjects also contributed sample s of knee joint fluid , for a total of seventy sample s from forty-seven subjects .  Lavage of the operatively treated , contralateral , and control knees was performed with the patient under regional anesthesia prior to arthroscopy , if applicable , by the infusion of sterile saline solution into the knee followed by the immediate withdrawal into a syringe . The concentrations of seventeen inflammatory cytokines and chemokines were measured with use of a multiplexed immunoassay panel . Preoperative magnetic resonance imaging findings and cytokine assay results were compared with intraoperative findings . RESULTS Multivariate analysis of variance detected significantly greater concentrations of interferon gamma ( IFN-gamma ) ; interleukins 2 , 4 , 6 , 10 , and 13 ( IL-2 , IL-4 , IL-6 , IL-10 , and IL-13 ) ; monocyte chemotactic protein-1 ( MCP-1 ) ; and macrophage inflammatory protein-1 beta ( MIP-1beta ) in fluid sample s from painful knees than in sample s from nonpainful knees . Correlation analysis demonstrated a significant positive correlation between patient-reported pain scores and concentrations of IL-6 ( Spearman rho = 0.7 ) , MCP-1 ( rho = 0.8 ) , MIP-1beta ( rho = 0.6 ) , and IFN-gamma ( rho = 0.6 ) . These four cytokines also demonstrated a positive correlation with each other ( rho = 0.5 to 0.7 ) . The presence of IFN-gamma , IL-6 , MCP-1 , or MIP-1beta performed as well as magnetic resonance imaging in the prediction of intraoperative findings . CONCLUSIONS Intra-articular concentrations of four inflammatory cytokines IFN-gamma , IL-6 , MCP-1 , and MIP-1beta correlated to pain in patients with symptomatic meniscal tears in the knee but were markedly lower in asymptomatic normal knees and in asymptomatic knees with meniscal tears . These cytokines may be involved in the generation of pain following meniscal injury STUDY DESIGN Descriptive , prospect i ve , longitudinal single-cohort study . OBJECTIVE To investigate the rate of force development to 30 % ( RFD(30 ) ) , 50 % ( RFD(50 ) ) , and 90 % ( RFD(90 ) ) of maximal voluntary isometric contraction ( MVIC ) as an adjunct outcome measure for determining readiness for return to sport following an  anterior cruciate ligament ( ACL ) reconstruction .  BACKGROUND One criterion of full recovery following an ACL reconstruction is the ability to achieve 85 % or 90 % of the maximal strength of the contralateral limb . However , the time required to develop muscular strength in many types of daily and sports activities is considerably shorter than that required to achieve maximal strength . Therefore , in addition to maximal strength , neuromuscular functions such as RFD should also be considered in the definition of recovery . METHODS Forty-five male professional soccer players who underwent an ACL reconstruction were recruited .  Assessment with the International Knee Documentation Committee ( IKDC ) Subjective Knee Evaluation Form , Tegner score , and KT1000 instrumented arthrometer  was performed postinjury/prereconstruction and at 6 and 12 months after ACL reconstruction .  MVIC , RFD(30 ) , RFD(50 ) , and RFD(90 ) testing was performed preinjury , as part of st and ard preseason assessment , and at 6 and 12 months post-ACL reconstruction . RESULTS The average MVIC value 6 months postreconstruction was 97 % of the preinjury average value . In contrast , at 6 months , the RFD(30 ) , RFD(50 ) , and RFD(90 ) values were 80 % ( P = .04 ) , 77 % ( P = .03 ) , and 63 % ( P = .007 ) , respectively , of the preinjury values . The mean RFD values for the reconstructed knee attained or exceeded 90 % of the preinjury mean values only at the 12-month post-ACL reconstruction assessment ( RFD(30 ) , P = .86 ; RFD(50 ) , P = .51 ; RFD(90 ) , P = .56 ) . CONCLUSION Despite the near recovery of MVIC strength to preinjury levels , there were still significant deficits in RFD at 6 months post-ACL reconstruction . An RFD similar to the preinjury RFD was achieved at 12 months post-ACL reconstruction , following a rehabilitation program focusing on muscle power . These results suggest that , following an ACL reconstruction , RFD criteria may be a useful adjunct outcome measure for the decision to return athletes to sports . J Orthop Sports Phys Ther 2012;42(9):772 - 780 , Epub 19 July 2012 . doi:10.2519/jospt.2012.3780 Background and Purpose Although various hop tests have been proposed as performance-based outcome measures following anterior cruciate ligament ( ACL ) reconstruction , limited reports of their measurement properties exist . The purpose of this study was to investigate the reliability and longitudinal validity of data obtained from hop tests during rehabilitation after ACL reconstruction . Subjects Forty-two patients , 15 to 45 years of age , who had undergone ACL reconstruction participated in the study . Methods and Measures The study design was prospect i ve and observational with repeated measures . The subjects performed a series of 4 hop tests on 3 separate occasions within the 16th week following surgery and on a fourth occasion 6 weeks later . The tests were a  single hop for distance  , a 6-m timed hop , a triple hop for distance  , and  crossover hops for distance .  Performance on the ACL-reconstructed limb was expressed as a percentage of the performance on the nonoperative limb , termed the “ limb symmetry index . ” Subjects also completed the Lower Extremity Functional Scale and a global rating of change question naire . Results Intraclass correlation coefficients for limb symmetry index values ranged from .82 to .93 . St and ard errors of measurement were 3.04 % to 5.59 % . Minimal detectable changes , at the 90 % confidence level , were 7.05 % to 12.96 % . Changes in hop test scores on the operative limb were statistically greater than changes on the nonoperative limb . Pearson correlations ( r ) between change in hop performances and self-reported measures ranged from .26 to .58 . Discussion and Conclusion The results show that the described series of hop tests provide a reliable and valid performance-based outcome measure for patients undergoing rehabilitation following ACL reconstruction . These findings support the use and facilitate the interpretation of hop tests for research and clinical practice CONTEXT The development pattern of motor coordination , strength , and functional ability during recovery from anterior cruciate ligament ( ACL ) reconstruction .  OBJECTIVE To investigate the relationship between motor coordination , functional ability , and strength after ACL reconstruction . DESIGN Prospect i ve clinical follow-up study . SETTING Sports-injury research laboratory . PARTICIPANTS 20 subjects who underwent ACL reconstruction .  INTERVENTIONS Real-time eccentric and concentric motor coordination were tested by a multijoint lower limb tracking-trajectory test , quadriceps and hamstring isokinetic strength were assessed by isokinetic dynamometer , and functional performance was tested with a single-leg-hop test 6 and 12 mo after ACL reconstruction . MAIN OUTCOME MEASURES Percentage deficits of the involved lower extremity for target-tracking ability , peak torque , total work parameters of isokinetic strength , and single-leg-hop distance . RESULTS Deficits in hamstring-quadriceps isokinetic muscle strength and single-leg-hop distance significantly decreased from the 6th to the 12th mo after surgery ( P < .05 ) . There were no significant differences in muscle concentric and eccentric motor-coordination deficits of the involved side ( P > .05 ) . CONCLUSIONS Although muscle strength and functional performance clearly increased from the 6th to the 12th mo after surgery , coordination characteristics of involved side remained low . This pattern demonstrated that motor-coordination progression was not affected by strength development . Patients continued to have significant motor-coordination deficits even 12 mo postsurgery . Therefore , the authors recommend that neuromuscular-coordination exercises be included in long-term rehabilitation programs to improve motor coordination Objective To evaluate the effectiveness of neuromuscular training in reducing the rate of acute knee injury  in adolescent female football players . Design Stratified cluster r and omised controlled trial with clubs as the unit of r and omisation . Setting 230 Swedish football clubs ( 121 in the intervention group , 109 in the control group ) were followed for one season ( 2009 , seven months ) . Participants 4564 players aged 12 - 17 years ( 2479 in the intervention group , 2085 in the control group ) completed the study . Intervention 
    Output:
    
The most commonly reported functional tests were the hop tests .
The knee flexion strength deficit was significantly less in the BPTB autograft group as compared with those having hamstring autograft at 1 year postoperatively , while no significant differences were found in isokinetic extension strength between the 2 groups .
Conclusion : Hop testing was the most commonly reported functional test following ACL reconstruction .
Increases in performance on functional tests were predictably seen as time increased following surgery .
Those with hamstring autografts may experience increased strength deficits with knee flexion versus those having BPTB autograft .