A single blinded randomised comparative study was done by Leung et al., (2003) to compare the effect of transcutaneous electrical nerve stimulation (TENS) and electro-acupuncture (EA) on osteoarthritis (OA) .
For the study 24 patients were selected (23 women and 1 man) mean age 85 were Divided into three groups. Group 1 (n=8) received EA of low frequency (2 Hz) , group 2 (n=8) received TENS (frequency 2 Hz and pulse width of 200 micros)both interventions Were givev on same 2 cupuncture points (ST-35,Dubi and EX-LE-4,Neixiya) for 20 minutes each given eight session for 2 weeks and group 3 or control group(n=8) .Main outcome measure for the study were pain and functional mobility measured by Number Rating Scale (NRS) and The Timed Up-and-Go Test(TUGT) respectively , all patients were assessed were assessed before the fist treatment, after the last treatment ,and at 2-week follow-up periods. Result of this study showed that there was significant reduction of knee pain in both EA and TENS group measured by (NRS) of pain (p < 0.01) and was maintained at a 2 -week follow- up and (TUGT) score of EA group was significantly lower than that of control group (p < 0.05) such change was not observed in TENS group. Hence the researcher concluded that both EA and TENS treatments were effective in reducing OA- induced knee pain.
Itoh et al., (2008) conducted a study to compare the effect of transcutaneous electrical nerve stimulation (TENS) , acupuncture or a combination of both for osteoarthritis (OA) . In their study researchers randomly assigned 32 patients with OA (21 women ,11 men; knee into four groups to receive specific weekly treatment five times during the study. Group 1or acupuncture group(ACP) received acupuncture ,group2 or TENS group received TENS, group 3 or acupuncture and TENS(A&T)group received TENS plus acupuncture and group 4 as control group (CT) received topical poultice (only when necessary) 2 patients from each group dropped out at follow-up so analysis were performed on 24 patients . The outcome measures were pain intensity measured using visual analogue scale (VAS) and knee function measured using western Ontario and McMaster osteoarthritis index (WOMAC) measured before starting(0 week ) and five weeks after the treatment. Result of this study showed that there was significant reduction in pain intensity VAS score (p = 0.039) and WOMAC score (p = 0.008) of A&T group than that of CT group. Hence through this study researcher concluded that combined acupuncture and TENS treatment was effective in pain relief and knee function improvement for patients suffering from knee OA.
Cheing and Hui-Chan (2004) examined whether addition of Transcutaneous electrical nerve stimulation (TENS ) to exercise training would produce better physical outcomes than TENS or exercise alone in people with knee osteoarthritis (OA). For this study Sixty-two patients with (OA) knee more than six month and able to walk on thair own for 10 minutes were randomly divided into four groups received either (1) TENS (TENS group) (140 ms square pulses at 80 Hz ) (n = 16,age 65.3 ±8.3, BMI 26.8 ±4.0) ,(2) placebo Stimulation (placebo group)(n = 16 , age 64.1 ±6.1, BMI 28.8 ±3.7) , (3) exercise training (exercise training group) (n = 15 , age 60.9 ±7.3, BMI 29.6 ±4.3) (4) TENS and exercise training(tens and exercise group) (n = 15, age 64.3 ±9.2, BMI 25.5 ±3.1) given five days a week for four weeks . Main outcome measures of the study were isometric peak torque measured by Cybex II + isokinetic dynamometer system, spatiotemporal gait parameters measures by foot-switch system and range of knee movement measured by Electrogoniometers were assessed in treatment session1 , session10 , session20 and the four week follow-up . Result of this study showed that an average of 26.6 % cumulative gain in knee extensor peak torque of the TENS and exercise group was recorded for the different knee position (p < 0.05) at session20 . Although the between-group difference Was short of being statistically significant, gained found in the TENS and exercise group was greater as compared to other three groups. The TENS and exercise group showed greater cumulative increase in stride length (12.6%, p = 0.006),walking cadence (9.3 % , p = 0.098) and gait velocity (22.4 %, p = 0.034) as compared to other groups. Significant increase in the range of knee motion during walking ( 12.0%, p = 0.000) was also recorded for the TENS and exercise group. Some improvement in physical outcomes were recorded for TENS group and Exercise group but negligible changes were found in Placebo group. Researcher concluded that no significant difference were found among the four treatment groups , but the addition of TENS to exercise training produced best Overall improvement in physical outcomes in people with knee osteoarthritis.
Yurtkuran et al., (1999) conducted a study to compare the effect of TENS , Electro acupuncture (EA) and Ice massage with placebo treatment for pain in osteoarthritis of the knee. For this study 100 patients with mean age 58.1 years (45-70 years) were randomly divided into four groups with n = 25 in each group. Group 1 received (TENS ), group 2 received electro acupuncture , group 3 received ice massage and placebo group.(TENS and EA: applied at 0.4-2.5 volt at frequency 4 Hz, pulse width of 100 ms for 20 minutes per session) . Main outcome of the study were pain at rest measured by visual analogue scale (VAS) quadriceps muscle strength, stiffness , knee flexion degree and 50 foot walking time measured after two weeks of treatment . Result of this study showed that there was significant reduction in pain and stiffness for TENS and EA (p < 0.01)in addition to ice massage (p < 0.05) .there was no significant effect in the placebo group . There was no significant difference between the result of three treatment groups. Researchers concluded that TENS , EA and Ice massage were effective in decreasing not only pain but also the objective parameters in a short period of time and treatment results of these ( TENS, EA and Ice massage )interventions were superior to placebo.
Cheing et al,.(2003) conducted a study to examined the optimal stimulation period and duration ( as measured by half life ) of post- stimulation analgesia of transcutaneous nerve stimulation (TENS) for relieving pain in osteoarthritis (OA) knee. for this study forty patients were recruited initially but during the study two patients dropped out from placebo group one due to renal problem and other due to work commitments.
Thirty – eight patients ( 34 were female and 4 men, grade II OA ) with mean age 65.5 years ( ranging from 51-79 years ) were randomly divided into four groups and received TENS( frequency 100 Hz with a pulse width of 200 ms) for either (i) 20 minutes TENS20 ) ( n =10, age 69.2years) (ii) 40 minutes (TENS40 ) ( n = 10 , age 63.2 years)
(iii) 60 minutes TENS 60 ) (iv) 60 minutes of placebo TENS (TENSPL ) ( n = 8 , 66.1 years) given 5 days a week for 2 weeks. Main outcome of the study was pain measure by visual analogue scale (VAS) significant reduction in VAS Score of three study groups ( TENS20, TENS 40 and TENS 60 ) were observed as compared to placebo group (TENSPL ) (p = 0.003) and greater cumulative reduction in VAS scale (from day 1to10) was found in the TENS 40 ( 83 .4%) group than in TENS 60 (68.37 %) , TENS20 (54.59%) and TENSPL (6.14%) groups ( p < 0.00) . By day 10 , half-life for the four groups was TENS20 (168 ± 32 ) , TENS 40 ( 256 ± 35 ) , TENS 60 (258 ± 49) TENSPL ( 35 ± 7 ) (p< 0.01 maintained for 2 weeks follow –up session ). Duration of post –stimulation analgesia period for TENS 40 (256 minutes) and TENS60 ( 258 minutes) groups was more prolonged than TENS20 (168 minutes) TENSPL (35 minutes) by day10 ( p< 0.00). TENS 40 showed longest pain relief period by the follow-up session . Researchers concluded that 40 minutes as optimal stimulation duration of TENS in OA knee for reduction of pain and post stimulation analgesia.