***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: OBJECTIVE To compare the effectiveness of transcutaneous electrical nerve stimulation ( TENS ) , interferential currents ( IFCs ) , and shortwave diathermy ( SWD ) against each other and sham intervention with exercise training and education as a multimodal package . DESIGN A double-blind , r and omized , controlled , multicenter trial . SETTING Departments of physical medicine and rehabilitation in 4 centers . PARTICIPANTS Patients ( N=203 ) with knee osteoarthritis ( OA ) . INTERVENTIONS The patients were r and omized by the principal center into the following 6 treatment groups : TENS sham , TENS , IFCs sham , IFCs , SWD sham , and SWD . All interventions were applied 5 times a week for 3 weeks . In addition , exercises and an education program were given . The exercises were carried out as part of a home-based training program after 3 weeks ' supervised group exercise . MAIN OUTCOME MEASURES Primary outcome was a visual analog scale ( 0 - 100 mm ) to assess knee pain . Other outcome measures were time to walk a distance of 15 m , range of motion , Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) , Nottingham Health Profile , and paracetamol intake ( in grams ) . RESULTS We found a significant decrease in all assessment parameters ( P<.05 ) , without a significant difference among the groups except WOMAC stiffness score and range of motion . However , the intake of paracetamol was significantly lower in each treatment group when compared with the sham groups at 3 months ( P<.05 ) . Also , the patients in the IFCs group used a lower amount of paracetamol  at 6 months ( P<.05 ) in comparison with the IFCs sham group . CONCLUSIONS Although all groups showed significant improvements , we can suggest that the use of physical therapy agents in knee OA provided additional benefits in improving pain because paracetamol intake was significantly higher in the patients who were treated with 3 sham interventions in addition to exercise and education The purpose of this study was to compare the effectiveness of transcutaneous nerve stimulation ( TENS ) , electroacupuncture ( EA ) , and ice massage with placebo treatment for the treatment of pain . Subjects ( n = 100 ) diagnosed with osteoarthritis ( OA ) of the knee were treated with these modalities . The parameters for evaluating the effectiveness of treatment include pain at rest , stiffness , 50 foot walking time , quadriceps muscle strength , and knee flexion degree . The results showed ( a ) that all three methods could be effective in decreasing not only pain but also the objective parameters in a short period of time ; and ( b ) that the treatment results in TENS , EA and ice massage were superior to placebo Background The present study tests whether a combined treatment of acupuncture and transcutaneous electrical nerve stimulation ( TENS ) is more effective than acupuncture or TENS alone for treating knee osteoarthritis ( OA ) . Methods Thirty-two patients with knee OA were r and omly allocated to four groups . The acupuncture group ( ACP ) received only acupuncture treatment at selected acupoints for knee pain ; the TENS group ( TENS ) received only TENS treatment at pain areas ; the acupuncture and TENS group ( A&T ) received both acupuncture and TENS treatments ; the control group ( CT ) received topical poultice ( only when necessary ) . Each group received specific weekly treatment five times during the study . Outcome measures were pain intensity in a visual analogue scale ( VAS ) and knee function in terms of the Western Ontario and McMaster Universities Osteoarthritis Index ( WOMAC ) . Results The ACP , TENS and A&T groups reported lower VAS and WOMAC scores than the control group . Significant reduction in pain intensity ( P = 0.039 ) and significant improvement in knee function ( P = 0.008 ) were shown in the A&T group . Conclusion Combined acupuncture and TENS treatment was effective in pain relief and knee function improvement for the sample d patients suffering from knee OA In the GRADE approach , r and omized trials start as high- quality evidence and observational studies as low- quality evidence , but both can be rated down if most of the relevant evidence comes from studies that suffer from a high risk of bias . Well-established limitations of r and omized trials include failure to conceal allocation , failure to blind , loss to follow-up , and failure to appropriately consider the intention-to-treat principle . More recently recognized limitations include stopping early for apparent benefit and selective reporting of outcomes according to the results . Key limitations of observational studies include use of inappropriate controls and failure to adequately adjust for prognostic imbalance . Risk of bias may vary across outcomes ( e.g. , loss to follow-up may be far less for all-cause mortality than for quality of life ) , a consideration that many systematic review s ignore . In deciding whether to rate down for risk of bias -- whether for r and omized trials or observational studies -- authors should not take an approach that averages across studies . Rather , for any individual outcome , when there are some studies with a high risk , and some with a low risk of bias , they should consider including only the studies with a lower risk of bias OBJECTIVE This study examined the optimal stimulation duration of transcutaneous electrical nerve stimulation ( TENS ) for relieving osteoarthritic knee pain  and the duration ( as measured by half-life ) of post-stimulation analgesia . SUBJECTS Thirty-eight patients received either : ( i ) 20 minutes ( TENS20 ) ; ( ii ) 40 minutes ( TENS40 ) ; ( iii ) 60 minutes ( TENS60 ) of TENS ; or ( iv ) 60 minutes of placebo TENS ( TENS(PL ) ) 5 days a week for 2 weeks . METHODS A visual analogue scale recorded the magnitude and pain relief period for up to 10 hours after stimulation . RESULTS By Day10 , a significantly greater cumulative reduction in the visual analogue scale scores was found in the TENS40 ( 83.40 % ) and TENS60 ( 68.37 % ) groups than in the TENS20 ( 54.59 % ) and TENS(PL ) ( 6.14 % ) groups ( p < 0.000 ) , such a group difference was maintained in the 2-week follow-up session ( p < 0.000 ) . In terms of the duration of post-stimulation analgesia period , the duration for the TENS40 ( 256 minutes ) and TENS60 ( 258 minutes ) groups was more prolonged than in the other 2 groups ( TENS20 = 168 minutes , TENS(PL ) = 35 minutes ) by Day10 ( p < 0.000 ) . However , the TENS40 group produced the longest pain relief period by the follow-up session . CONCLUSION 40 minutes is the optimal treatment duration of TENS , in terms of both the magnitude ( VAS scores ) of pain reduction and the duration of post-stimulation analgesia for knee osetoarthritis Abstract Objective : To study the effects of transcutaneous electrical nerve stimulation ( TENS ) on joint position sense ( JPS ) in knee osteoarthritis ( OA ) subjects . Methods : Thirty subjects with knee OA ( 40–60 years old ) using non-r and om sampling participated in this study . In order to evaluate the absolute error of repositioning of the knee joint , Qualysis Track Manager system was used and sensory electrical stimulation was applied through the TENS device . Results : The mean errors in repositioning of the joint , in two position of the knee joint with 20 and 60 degree angle , after applying the TENS was significantly decreased ( p < 0.05 ) . Conclusion : Application of TENS in subjects with knee OA could improve JPS in these subjects Cetin N , Aytar A , Atalay A , Akman MN : Comparing hot pack , short-wave diathermy , ultrasound , and TENS on isokinetic strength , pain , and functional status of women with osteoarthritic knees : a single-blind , r and omized , controlled trial . Am J Phys Med Rehabil 2008;87:443–451 . Objective : To investigate the therapeutic effects of physical agents administered before isokinetic exercise in women with knee osteoarthritis . Design : One hundred patients with bilateral knee osteoarthritis were r and omized into five groups of 20 patients each : group 1 received short-wave diathermy + hot packs and isokinetic exercise ; group 2 received transcutaneous electrical nerve stimulation + hot packs and isokinetic exercise ; group 3 received ultrasound + hot packs and isokinetic exercise ; group 4 received hot packs and isokinetic exercise ; and group 5 served as controls and received only isokinetic exercise . Results : Pain and disability index scores were significantly reduced in each group . Patients in the study groups had significantly greater reductions in their visual analog scale scores and scores on the Lequesne index than did patients in the control group ( group 5 ) . They also showed greater increases than did controls in muscular strength at all angular velocities . In most parameters , improvements were greatest in groups 1 and 2 compared with groups 3 and 4 . Conclusions : Using physical agents before isokinetic exercises in women with knee osteoarthritis leads to augmented exercise performance , reduced pain , and improved function . Hot pack with a transcutaneous electrical nerve stimulator or short-wave diathermy has the best outcome It is not clear whether segmental innocuous stimulation has a stronger analgesic effect than segmental noxious stimulation for chronic pain and whether the fading of current sensation during treatment interferes with the analgesic effect , as suggested by the gate control theory . Electrical stimulation ( by way of Interferential Current ) applied at the pain area ( segmental ) was administered to 4 groups of patients with osteoarthritis ( OA ) knee pain . Two groups were administered with noxious stimulation ( 30 % above pain threshold ) and two with innocuous stimulation ( 30 % below pain threshold ) . In each group half of the patients received a fixed current intensity while the other half raised the intensity continuously during treatment whenever fading of sensation was perceived . Group 5 and 6 received sham stimulation and no treatment , respectively . The outcome measures were : chronic pain intensity , morning stiffness , range of motion ( ROM ) , pain threshold and % pain reduction . Both noxious and innocuous stimulation significantly decreased chronic pain ( P<0.001 ) and morning stiffness ( P<0.01 ) and significantly increased pain threshold ( P<0.001 ) and ROM ( P<0.001 ) compared with the control groups . Nevertheless , noxious stimulation decreased pain intensity ( P<0.05 ) and increased pain threshold ( P<0.001 ) significantly more than innocuous stimulation . No differences in treatment outcomes were found between adjusted and unadjusted stimulation . ( a ) Interferential current is very effective for chronic OA knee pain , ( b ) segmental noxious stimulation produces a stronger analgesic effect than segmental innocuous stimulation , ( c ) the fading of sensation during treatment , does not decrease the analgesic effect . Possible mechanisms explaining the findings are discussed Background : According to a recent meta analysis study , there is strong evidence to support the view that transcutaneous electrical nerve stimulation ( TENS ) is an effective treatment for managing osteoarthritis ( OA ) knee pain . However , there is limited evidence showing its effectiveness in improving physical function . This study examined whether TENS alone can improve physical function in terms of range of knee motion and the Timed-Up- and -Go Test . Methods : Subjects were r and omly allocated into 2 groups receiving TENS at 100 Hz or a placebo TENS . Outcome measures included : 1 ) visual analog scale for measuring the intensity of the present pain , 2 ) Timed-Up- and -Go Test , and 3 ) range of knee motion ( ROM ) . Repeated- measures analysis of variance and Pearson correlation were used for data analyses . Results : By day 10 , TENS produced a significantly greater increase in maximum knee ROM than the placebo group ( P = 0.033 ) . TENS also significantly increased the pain-limited knee ROM across sessions , but the between-group difference was short of significance ( P = 0.067 ) . The decrease in time in performing the Timed-Up- and -Go Test was also not significantly different between the 2 groups . A moderate correlation was observed between the reduction in pain scores and the improvement in the Timed-Up- and -Go Test . Conclusions : Our findings suggested that TENS did improve some of the physical parameters but over 10 days was unable to produce significant improvement in functional performance among people with knee OA . A larger-scale study with the assessment of other functional outcomes may be required to clarify if TENS could improve function in people with knee OA . Also , exercise can be considered to be an important adjunct treatment to TENS to improve function significantly OBJECTIVE This is a double blind study that examined the optimal stimulation frequency of transcutaneous electrical nerve stimulation in reducing  pain due to knee osteoarthritis . SUBJECTS Thirty-four subjects were r and omly allocated into 4 groups receiving transcutaneous electrical nerve stimulation at either : ( i ) 2 Hz ; ( ii ) 100 Hz ; ( iii ) an alternating frequency of 2 Hz and 100 Hz ( 2/100 Hz ) ; or ( iv ) a placebo transcutaneous electrical nerve stimulation . METHODS Treatment was administered 5 days a week for 2 weeks . The outcome measures included : ( i ) a visual analogue scale ; ( ii ) a timed up- and -go test ; and ( iii ) a range of knee motion . RESULTS The 3 active transcutaneous electrical nerve stimulation groups ( 2 Hz , 
    Output:
    
DISCUSSION TENS might relieve pain due to knee osteoarthritis .