***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 
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    Input: Background Self-reported knee pain is highly prevalent among adolescents . As much as 50 % of the non-specific knee pain may be attributed to Patellofemoral Pain Syndrome ( PFPS ) . In the short term , exercise therapy appears to have a better effect than patient education consisting of written information and general advice on exercise or compared with placebo treatment . But the long-term effect of exercise therapy compared with patient education is conflicting . The purpose of this study is to examine the short- and long-term effectiveness of patient education compared with patient education and multimodal physiotherapy applied at a very early stage of the condition among adolescents . Methods / Design This study is a single blind pragmatic cluster r and omised controlled trial . Four upper secondary schools have been invited to participate in the study ( approximately 2500 students , aged 15 - 19 years ) . Students are asked to answer an online question naire regarding musculoskeletal pain . The students who report knee pain are contacted by telephone and offered a clinical examination by a rheumatologist . Subjects who fit the inclusion criteria and are diagnosed with PFPS are invited to participate in the study . A minimum of 102 students with PFPS are then cluster-r and omised into two intervention groups based on which school they attend . Both intervention groups receive written information and education . In addition to patient education , one group receives multimodal physiotherapy consisting primarily of neuromuscular training of the muscles around the foot , knee and hip and home exercises . The students with PFPS fill out self-reported question naires at baseline , 3 , 6 , 12 and 24 months after inclusion in the study . The primary outcome measure is perception of recovery measured on a 7-point Likert scale ranging from " completely recovered " to " worse than ever " at 12 months . Discussion This study is design ed to investigate the effectiveness of patient education compared with patient education combined with multimodal physiotherapy . If patient education and multimodal physiotherapy applied at an early stage of Patellofemoral Pain Syndrome proves effective , it may serve as a basis for optimising the clinical pathway for those suffering from the condition , where specific emphasis can be placed on early diagnosis and early treatment . Trial Registration clinical trials.gov reference : Objectives Describe proportions of individuals with patellofemoral pain ( PFP ) with an unfavourable recovery over 12 months ; identify clinical predictors of poor recovery at 3 and 12 months ; and determine baseline values of predictors that identify those with poor 12-month prognosis . Methods An observational analysis utilised data from 310 individuals with PFP enrolled in two r and omised clinical trials . Thirteen baseline variables ( participant , PFP , study characteristics ) were investigated for their prognostic ability . Pain , function and global recovery were measured at 3 and 12 months . Multivariate backward stepwise regression analyses ( treatment-adjusted , p<0.10 ) were performed for each follow-up measure . Receiver operator characteristic curves identified cut-points associated with unfavourable recovery at 12 months . Results 55 % and 40 % of participants had an unfavourable recovery at 3 and 12 months , respectively . Longer baseline pain duration was significantly associated with poor 3-month and 12-month recovery on measures of pain severity ( β 11.36 to 24.94 ) , Anterior Knee Pain ( AKP ) Scale ( −4.44 to −11.33 ) and global recovery ( OR : 2.32 to 6.11 ) . Greater baseline pain severity and lower AKP Scale score were significantly associated with poor recovery on multiple measures ( p<0.05 ) . Baseline duration > 2 months and AKP Scale score < 70/100 were associated with unfavourable 12-month recovery . Conclusions A substantial number of individuals with PFP have an unfavourable recovery over 12 months , irrespective of intervention . Knee pain duration > 2 months is the most consistent prognostic indicator , followed by AKP Scale score < 70 . Sports medicine practitioners should utilise interventions with known efficacy in reducing PFP , and promote early intervention to maximise prognosis . Trial registration Australian study : Australian Clinical Trials Registry ( ACTRN012605000463673 ) , Clinical Trials.gov ( NCT00118521 ) ; Dutch study : International St and ard R and omised Controlled Trial Number Register ( IS RCT N83938749 OBJECTIVE To determine the effects of electromyographic biofeedback treatment in patients with patellofemoral pain syndrome . DESIGN R and omized controlled trial . SETTING A physical medicine and rehabilitation department in a research hospital of a university referral center . PATIENTS Sixty patients with patellofemoral pain syndrome . Patients were r and omly placed into 2 groups : biofeedback group ( n = 30 ) and a control group ( n = 30 ) . INTERVENTION The biofeedback group received electromyographic biofeedback training and a conventional exercise program , whereas the control group received a conventional exercise program only . MAIN OUTCOME MEASURES Maximum and mean contraction values of the vastus medialis and the vastus lateralis muscles were assessed with the biofeedback device . Pain and functional status of the patients were measured by a visual analog scale ( VAS ) and the Functional Index Question naire ( FIQ ) , respectively . RESULTS Contraction values improved significantly at the end of the first month , compared with the pretreatment values in both groups . Mean contraction values in the biofeedback group of the vastus medialis muscles in all 3 monthly measurements , and the vastus lateralis muscles at the end of the first month , were significantly higher than those of the control group . Significant improvements were shown for both the VAS and the FIQ in both groups . Monthly follow-ups showed no VAS and FIQ differences between the groups . CONCLUSION Electromyographic biofeedback treatment did not result in further clinical improvement when compared with a conventional exercise program in patients with patellofemoral pain syndrome Purpose Neuromuscular electrical stimulation ( NMES ) with large electrodes and multiple current pathways ( m-NMES ) has recently been proposed as a valid alternative to conventional NMES ( c-NMES ) for quadriceps muscle (re)training . The main aim of this study was to compare discomfort , evoked force and fatigue between m-NMES and c-NMES of the quadriceps femoris muscle in healthy subjects . Methods Ten healthy subjects completed two experimental sessions ( c-NMES and m-NMES ) , that were r and omly presented in a cross-over design . Maximal electrically evoked force at pain threshold , self-reported discomfort at different levels of evoked force , and fatigue-induced force declines during and following a series of 20 NMES contractions were compared between c-NMES and m-NMES . Results m-NMES result ed in greater evoked force ( P < 0.05 ) and lower discomfort in comparison to c-NMES ( P < 0.05–0.001 ) , but fatigue time course and magnitude did not differ between the two conditions . Conclusions The use of quadriceps m-NMES appears legitimate for (re)training purpose s because it generated stronger contractions and was less discomfortable than c-NMES ( due to multiple current pathways and /or lower current density with larger electrodes ) Abstract Traditional conservative treatment for patellar disorders is successful in about 80 percents of cases . We introduced two new conservative treatment protocol s for patellar pathology in order to further improve the success rate . The first protocol consisted of high load/low repetition quadriceps femoris training ( 10 patients )  while the second enclosed selective electrostimulation of vastus medialis muscle  ( 7 patients ) . Results were evaluated clinical ly and neurophysiologically . High load/low repetition training result ed in significant increase of maximal voluntary contraction of quadriceps muscle ( P < 0.001 ) . Significant gain of Activity ( P = 0.017 ) and Kujala scores ( P = 0.07 ) was observed in group with high load/low repetition quadriceps training compared to patients with electrostimulation . There was no significant change in neurophysiological or clinical status between the beginning and the end of treatment with electrostimulation . Our results indicate that high load/low repetition quadriceps femoris training poses an important alternative to traditional conservative treatment protocol for patellar disorders OBJECTIVE To compare a commercially available electric muscle stimulation regimen with a novel form of stimulation for the rehabilitation of the quadriceps muscle , in patients with patellofemoral pain syndrome . DESIGN Double-blinded r and omized trial with a parallel control group and stratified r and omization . SETTING Home-based rehabilitation program assessed in research center . PARTICIPANTS Eighty patients ( 47 women , 33 men ) with patellofemoral pain syndrome . INTERVENTIONS One group ( EMPI ) received 1 uniform constant frequency component of 35Hz . The other ( EXPER ) group received an experimental form of stimulation that contained 5 simultaneously delivered frequency components of 125 , 83 , 50 , 2.5 , and 2Hz . Stimulation was applied to the quadriceps muscles of the affected leg for 1 hour daily for 6 weeks , a total of 42 treatments . MAIN OUTCOME MEASURES Lower-limb isometric and isokinetic torque , quadriceps fatigue , knee flexion , patellar pain , a step test , quadriceps cross-sectional area , and Kujala patellofemoral score for pain before and after treatment . RESULTS Seventy-four patients ( 43 women , 31 men ) completed the trial . Patients in both groups showed significant improvements in all outcomes ( P<.05 ) . No significant differences existed between the 2 stimulators in any outcome ( P>.05 ) except for quadriceps cross-sectional area ( P=.023 ) . CONCLUSIONS One form of stimulation was just as efficacious as the other in improving subjective and objective measures A linear analogue for rating  pain with 10 , 15 and 20 cm lines is significantly less variable than a 5 cm line ( mean error of 15 cm line is 0 - 19 % , 95 % confidence limits for the group + /- 2 % and an inood correlation between repeated ratins of a recalled pain distant in time . The variance of the rating is significantly less than the repeated rating of a r and om mark . The linear analogue rating of a constant pain stimulus is reproducible and changes in rating are likely to be real changes of opinion . Pethidine 150 mg intramuscularly had no significant effect , tested 30 minutes after the administration , on the accuracy or reproducibility of the analogue rating . A linear analogue seems a suitable method of recording the patient 's opion of a severe pain such as that of labour The aim of this study was to assess the clinical efficacy and safety of NMES program applied in male soccer players ( after ACL reconstruction ) on the quadriceps muscle . The 80 participants ( NMES = 40 , control = 40 ) received an exercise program , including three sessions weekly . The individuals in NMES group additionally received neuromuscular electrical stimulation procedures on both right and left quadriceps ( biphasic symmetric rectangular pulses , frequency of impulses : 2500 Hz , and train of pulses frequency : 50 Hz ) three times daily ( 3 hours of break between treatments ) , 3 days a week , for one month . The  tensometry , muscle circumference , and goniometry pendulum test  ( follow-up after 1 and 3 months ) were applied . The results of this study show that NMES ( in presented parameters in experiment ) is useful for strengthening the quadriceps muscle in soccer athletes . There is an evidence of the benefit of the NMES in restoring quadriceps muscle mass and strength of soccer players . In our study the neuromuscular electrical stimulation  appeared to be safe for biomechanics of knee joint . The pathological changes in knee function were not observed . This trial is registered with Australian and New Zeal and Clinical Trials Registry ACTRN12613001168741 PURPOSE Although physical therapy is known to be effective in treating patellofemoral pain ( PFP ) , there is considerable individual variation in the treatment response . It is unclear why some patients benefit from a specific treatment while others do not experience improvement . This study , using a prospect i ve study design , aims to identify factors that could predict the short-term functional outcome and account for the variation frequently seen in the outcome after conservative treatment of PFP . METHODS Thirty-six patients ( 20 female and 16 male with a mean age of 23.8 ± 6.7 yr ) followed a physical therapy rehabilitation program of 7 wk . Before this treatment , all patients were evaluated on subjective symptoms ( pain on visual analog scales in millimeters ) and  functional performance  ( step test expressed as highest level , single-legged hop test in centimeters , and triple-hop test in centimeters ) . The concentric and eccentric knee extensor strength at 60 ° .s(-1 ) and 240 ° .s(-1 ) ( N.m ) were measured as well as the quadriceps muscle size by calculating the cross-sectional area ( cm(2 ) ) with magnetic resonance imaging . The success of the treatment was evaluated by the functional Kujala anterior knee pain scale . A linear regression model was used to identify predisposing factors for the functional outcome . RESULTS The total quadriceps cross-sectional area ( P = 0.010 ) , the eccentric average peak torque at 60 ° .s(-1 ) ( P = 0.015 ) , and the frequency of pain at baseline ( P = 0.012 ) have been indicated as predisposing variables in the short-term functional outcome after a physical therapy rehabilitation program for PFP ( adjusted R(2 ) = 0.46 ) . CONCLUSION Patients with a greater quadriceps 
    Output:
    
The very low- quality evidence available means that we are uncertain whether or not a multiple-session programme of NMES combined with exercise over several weeks versus exercise alone results in clinical ly important differences in knee pain and function at the end of the treatment period or at one year .
There were no data on adverse effects such as muscle fatigue and discomfort .