osteoarthritis ( oa ) is the most common form of arthritis characterized pathologically by both focal loss of articular cartilage and marginal and central new bone formation . although biomechanical and biochemical processes occur mainly on the articular cartilage , the entire joint , including subchondral bone , synovial membrane , joint capsule , and ligaments , are affected in oa . cytokines ( il-1 and tnf - b ) activate enzymes causing proteolytic digestion of cartilage and tissue growth factor and insulin growth factor causes cartilage synthesis . when catabolism exceeds cartilage synthesis , oa develops . after few years , the reparative process exhausted and this leaves cartilage degradation unopposed leading to progressive oa , which results into inflammation , pain , and structural damage leading to loss of function . oa disease causes pain , swelling , and loss of motion of the joint due to the bones under the cartilage rubbing together . endogenous factors such as age , sex , hereditary , post - menopausal changes , exogenous factors such as macro trauma , lifestyle factors such as ( alcohol , tobacco ) , obesity , or overweight , repetitive joint surgery leads to oa . pharmacological drugs such as non - opioid analgesics , opioid and topical analgesics , nsaid , hyaluronic acid injections , and intra - articular steroid injections are given in the initial stages . surgical procedures such as cartilage repair techniques , osteotomy , and tka can also performed in later stages . various interventions such as acupuncture , laser , tens , ultrasound , hydrotherapy , and manual therapy techniques can be applied for acute and chronic stages and braces and orthosis are prescribed for the supportive purposes . yoga is one intervention which has off late been considered as a treatment for oa . of the various schools of yoga , iyengar yoga is a form of hatha yoga created by bks iyengar and stresses strength , balance , breathing , and the alignment of the body . it allows the use of various assistive devices such as chairs or blocks to aid balance and straps to facilitate stretching . because the body can be supported and balanced by these techniques , beginners can achieve many postures that would otherwise be literally , out of reach . emg biofeedback is generally used to provide muscle re - education and to regain muscle strength in cases of muscle weakness . a patient 's compliance to the exercise program can be improved by addition of emg biofeedback to the rehabilitation programs . emg biofeedback assisted exercise programs are suggested as they increase compliance with exercise and motivation of patients . though individual effects of different treatment modalities are discussed in various studies , there is lack of evidence in understanding the combined effect of iyengar yoga with physiotherapy methods . thus the purpose of the study is to find out if there is any additional effect of iyengar yoga when combined with conventional physiotherapy for chronic unilateral knee thirty ( n = 30 ) subjects between 45 and 70 years of age , having symptomatic oa knee for at least 6 months before study entry and who were not currently participating in any exercise program , were divided using systematic sampling into two groups ( groups a and b ) . both male and female pparticipants who had grade 2 or 3 as criteria of kellgren and lawrence with at least two of the following symptoms : ( 1 ) stiffness 30 minutes , ( 2 ) crepitus , bony tenderness , ( 3 ) bony enlargement , or ( 4 ) absence of palpable warmth were included in the study . patients diagnosed as a case of unilateral knee oa , having  6 cm in visual analog scale ( vas ) , with symptoms of locking or instability , secondary oa , trauma during last 3 months , and axial deviation > 15 in valgus / varus were excluded from the study . patients having diseases of other systems that could have created difficulty during the study follow - up , chronic use of a knee brace , cane , or walker ; or a prior diagnosis of inflammatory arthritis , severe oa ( stage 4 according to kellegren and lawrence radiological classification ) were also not included in the study . the first patient was allocated to group a and second patient was allocated to group b accordingly , thus group a ( n = 15 ; iyengar yoga , emg biofeedback , knee strengthening exercise and tens ) and group b ( n = 15 ; emg biofeedback , knee strengthening exercise and tens ) . the sociodemographic characteristics of the patients are provided in table 1 . demographic details of group - a and group b the study has been approved by the institutional scientific committee and institutional ethical committee . all the participants completed all the sessions of intervention ( no drop outs ) . during the treatment sessions none of vas involves a 10-cm horizontal line with no pain anchored at the left end and pain as bad as it could be anchored at the right end . the patients were asked to place a mark on the line that represented the severity of his or her pain at the moment . this list contains some sentences that people have used to describe themselves when they have trouble with their knee . there is maximum 10 score for pain , 8 score for stiffness , and 68 score for physical function . it is a reliable and valid instrument for measuring the disability in chronic unilateral knee oa patients . the above outcome measures were assessed at baseline and after 8 weeks of intervention in group a and group b. 3 times / week for 8 weeks , 1 session 90 minutes . in this iyengar yoga , assistive devices such as blocks , belts , and blankets were used to support the parts of the body while perform the asana . all participants were encouraged to stretch as fully as possible while not exceeding the limits of their comfort and were encouraged to use props as needed . all the asanas were performed for three repetitions / sessions . list of asanas performed in modified iyengar yoga is provided in table 2 . types of yoga applied and its dosage for 8 weeks with 45 duration of each session was provided for the quadriceps muscles . two active surface electrodes were placed parallel to the muscle fibers and inactive ones were placed at equal distances far from the two active electrodes . this equipment shows muscle activity obtained during exercises with visual and auditory signals , increasing with increments in muscle activity . thus , the patient got a feedback about how much muscle contractions were made during exercise . 3 times / week , 3 sets of 1015 repetitions for 8 weeks . the basic program exercises that were provided were straight leg raise , short - arc lift , side lying abduction , standing hamstring curl , and toe raise . frequency , 0100 hz ; pulse duration , 50 ms ; size of electrode , 5  7 cm 2 electrode , the lateral and medial knee ; treatment time , 20 minutes . p values < 0.05 were accepted as indicating significant differences between pre - and post - intervention data . thirty ( n = 30 ) subjects between 45 and 70 years of age , having symptomatic oa knee for at least 6 months before study entry and who were not currently participating in any exercise program , were divided using systematic sampling into two groups ( groups a and b ) . both male and female pparticipants who had grade 2 or 3 as criteria of kellgren and lawrence with at least two of the following symptoms : ( 1 ) stiffness 30 minutes , ( 2 ) crepitus , bony tenderness , ( 3 ) bony enlargement , or ( 4 ) absence of palpable warmth were included in the study . patients diagnosed as a case of unilateral knee oa , having  6 cm in visual analog scale ( vas ) , with symptoms of locking or instability , secondary oa , trauma during last 3 months , and axial deviation > 15 in valgus / varus were excluded from the study . patients having diseases of other systems that could have created difficulty during the study follow - up , chronic use of a knee brace , cane , or walker ; or a prior diagnosis of inflammatory arthritis , severe oa ( stage 4 according to kellegren and lawrence radiological classification ) were also not included in the study . the first patient was allocated to group a and second patient was allocated to group b accordingly , thus group a ( n = 15 ; iyengar yoga , emg biofeedback , knee strengthening exercise and tens ) and group b ( n = 15 ; emg biofeedback , knee strengthening exercise and tens ) . the sociodemographic characteristics of the patients are provided in table 1 . demographic details of group - a and group b the study has been approved by the institutional scientific committee and institutional ethical committee . all the participants completed all the sessions of intervention ( no drop outs ) . during the treatment sessions none of vas involves a 10-cm horizontal line with no pain anchored at the left end and pain as bad as it could be anchored at the right end . the patients were asked to place a mark on the line that represented the severity of his or her pain at the moment . this list contains some sentences that people have used to describe themselves when they have trouble with their knee . there is maximum 10 score for pain , 8 score for stiffness , and 68 score for physical function . it is a reliable and valid instrument for measuring the disability in chronic unilateral knee oa patients . the above outcome measures were assessed at baseline and after 8 weeks of intervention in group a and group b. 3 times / week for 8 weeks , 1 session 90 minutes . in this iyengar yoga , assistive devices such as blocks , belts , and blankets were used to support the parts of the body while perform the asana . all participants were encouraged to stretch as fully as possible while not exceeding the limits of their comfort and were encouraged to use props as needed . types of yoga applied and its dosage for 8 weeks with 45 duration of each session was provided for the quadriceps muscles . two active surface electrodes were placed parallel to the muscle fibers and inactive ones were placed at equal distances far from the two active electrodes . this equipment shows muscle activity obtained during exercises with visual and auditory signals , increasing with increments in muscle activity . thus , the patient got a feedback about how much muscle contractions were made during exercise . the basic program exercises that were provided were straight leg raise , short - arc lift , side lying abduction , standing hamstring curl , and toe raise . frequency , 0100 hz ; pulse duration , 50 ms ; size of electrode , 5  7 cm 2 electrode , the lateral and medial knee ; treatment time , 20 minutes . p values < 0.05 were accepted as indicating significant differences between pre - and post - intervention data . 3 times / week for 8 weeks , 1 session 90 minutes . in this iyengar yoga , assistive devices such as blocks , belts , and blankets were used to support the parts of the body while perform the asana . all participants were encouraged to stretch as fully as possible while not exceeding the limits of their comfort and were encouraged to use props as needed . for 8 weeks with 45 duration of each session was provided for the quadriceps muscles . two active surface electrodes were placed parallel to the muscle fibers and inactive ones were placed at equal distances far from the two active electrodes . this equipment shows muscle activity obtained during exercises with visual and auditory signals , increasing with increments in muscle activity . thus , the patient got a feedback about how much muscle contractions were made during exercise . 3 times / week , 3 sets of 1015 repetitions for 8 weeks . emphasis was to build muscle strength using both legs . the basic program exercises that were provided were straight leg raise , short - arc lift , side lying abduction , standing hamstring curl , and toe raise . frequency , 0100 hz ; pulse duration , 50 ms ; size of electrode , 5  7 cm 2 electrode , the lateral and medial knee ; treatment time , 20 minutes . p values < 0.05 were accepted as indicating significant differences between pre - and post - intervention data . the baseline values of vas ( p = 0.233 ) and modified womac score ( p = 0.245 ) showed no significant difference ( p > 0.05 ) between in either of the groups a and b suggesting that sample assignment was successful . compared to the baseline values , group a showed a more reduced vas ( 56.83% ) and modified womac ( 59.21% ) score than group b ( vas 38.15% and modified womac 34.08% ) after 8 weeks of intervention . the pre- and post - intervention ratings of vas and modified womac score showed a statistically significant reduction of pain intensity and functional disability in group a compared with group b ( p < 0.05 ) shown in table 3 . mann whitney of visual analog scale  pain and western ontario mcmaster universities scale statistical analysis also showed 56.83% improvement in group a and 38.15% improvement in group b. when comparing the percentage of reduction of pain intensity between groups a and b , group a showed more reduction in pain intensity at the end of the treatment ( after 8 weeks ) when compared with group b. further with respect to reduction in functional disability , group a showed 59.21% improvement , whereas group b showed only 34.08% improvement at the end of the treatment ( after 8 weeks ) . the above results depict that an addition of iyengar yoga combined with emg biofeedback , knee muscle strengthening exercises , and tens is effective in reducing pain and functional disability . this result validates those of earlier studies that have depicted that yoga provides a safe and feasible exercise option for yoga - naive , obese patients over  50 years of age and offers potential reductions in pain and disability caused by oa . in yoga , specific asanas that strengthen the quadriceps and other muscles relieve physical stress on the knee joint . different postures focus on flexibility and increased blood flow , presumably by aligning joints , including the ankles , knees , and hips . standing postures strengthen and align bones and muscles , particularly of the lower extremities . stretching is achieved by bending and twisting . traction and active alignment from the use of one 's own muscles , if tolerated , is preferable to passive traction by the use of external postures . further , the cellular effects of mechanical and fluid pressure on structures such as cartilage suggest that yoga postures might alter joint function . low levels of intermittent fluid pressure , as occurring during joint distraction , have been shown in vitro to decrease production of catabolic cytokines , such as interleukin-1 and tumor necrosis factor-. in experimental settings , joint motion preserves cartilage that can be lost by immobilization . correctly supervised yoga may be one way to provide the motion and forces on joints needed to preserve integrity . quadriceps strengthening has long been noted to be of importance in the development of knee oa , and there is ample evidence that muscle - strengthening exercises improve pain reduction and functional disability . asanas using assistive devices emphasize stretching thus may be of particular benefit in treating oa . in this context it can be stated that iyengar yoga could be best - suited yoga style for treatment of oa . a larger sample would be required to validate and generalize the results of this study to the population . further the design did not support long - term follow - up of the patients after the study , to understand if they continued practicing yoga and deriving benefits from its practice even after completion of the study . iyengar yoga as an add on treatment in combination with emg biofeedback , knee muscle strengthening exercise , and tens can be used as choice viable of treatment for patient with chronic unilateral tibiofemoral oa in terms of pain and functional disability .
background : there are limited data about iyengar yoga and emg biofeedback in knee oa , although the efficacy of emg biofeedback in the rehabilitation of patients with quadriceps muscle weakness secondary to immobilization , contracture , and joint surgery has been well established.materials and methods : thirty subjects who have fulfilled inclusion and exclusion criteria were selected and divided into two groups ( group a and b ) . both the groups were treated with emg biofeedback , knee muscle strengthening exercises , and tens . 
 group a received additionally iyengar yoga for 8 weeks . 
 both groups were evaluated by visual analog scale and modified womac 
 western ontario mcmaster universities scale.results:patients in both groups experienced significant reduction in pain and improvement in functional ability . in vas scale group a showed reduction of 56.83% ( p = 0.001 ) when compared with group b 38.15% ( p  0.001 ) . 
 in modified womac scale , group a showed reduction of 59.21% ( p = 0.001 ) when compared with group b 34.08% ( p = 0.001).conclusion : adding iyengar yoga along with conventional therapy provides better results in chronic unilateral knee osteoarthritis in terms of pain and functional disability .