this condition can range from mild discomfort to severe pain that limits activities of daily living .
conservative management of hip pain includes paracetamol , nonsteroidal anti - inflammatory drugs ( nsaids ) , narcotics , and physical modalities.1,2 patients who fail to respond to conservative treatment usually undergo surgery .
often , surgery is not an option for patients with multiple comorbidities and conventional drugs either have many side effects or are ineffective.3,4 percutaneous pulsed radiofrequency ( prf)1 or conventional radiofrequency ( crf)26 of the articular branches of the obturator and femoral nerves is a novel alternative treatment for hip pain that has been previously reported in literature .
however , the efficacy of prf or crf in hip pain is not well established because comparative studies with conservative management have not been conducted
. there are only anecdotal evidences in the literatures.16 prf is a new method in rf treatment of pain .
it is a non - neurolytic lesioning method for pain relief and can relieve pain without evidence of neural damage.7,8 in the present prospective , nonrandomized , open - label study , we attempt to compare the efficacy of prf relative to conservative management for chronic hip pain .
patients suffering from chronic hip pain for > 3 months with radiographic osteoarthritis of the hip ( tnnis grades i and ii ) were approached for this study .
patients presented with pain on a range of motions , groin and thigh pain , and limitation of range of motion , especially internal rotation .
patients also underwent various combinations of imaging studies ( plain films , computed tomography , or magnetic resonance imaging ) to diagnose and exclude other causes of pain originating from spine , sacroiliac joint , or other sources . between august 2011 and july 2013
exclusion criteria comprised refusal to participate , extrinsic source of hip pain ( eg , lumbar radiculopathy ) , pain related to bony fracture , avascular necrosis of hip , postsurgical pain , anticoagulation therapy , local infection over buttock and hip , systemic sepsis , allergy to local anesthetics , psychiatric illness , and inability to comprehend pain scoring .
the patients were divided into two groups ( prf and conservative treatment ) according to consent or refusal to undergo prf procedure .
fourteen patients who declined prf because of the possibility of prf complications were managed conservatively .
these patients received exercise programs and medications , including paracetamol , nsaids , and/or narcotic drugs for chronic hip pain .
patients who declined prf were evaluated longitudinally and served as controls . in the prf group
patients who received conservative treatment but who still had severe pain could receive prf procedure after 12 weeks treatment if they wanted to cross over .
the techniques for radiofrequency ( rf ) lesioning of the articular branches of the femoral and obturator nerves are described elsewhere.1,9,10 prf was performed under strict sterile conditions in an operating room .
each patient was placed in a supine position , and the skin overlying the operation area was prepared and draped .
a standard rf lesion generator ( neurotherm jk 25 t ) was used for the whole procedure .
after administration of local anesthesia ( 2% lidocaine ) , a 22-gauge 10-mm active tip rf cannula ( neurotherm ) 10 cm in length was inserted and advanced toward the articular branches of the obturator and femoral nerves ( figure 1 ) .
denervation of the sensory branches of the obturator and femoral nerves using prf was performed in all the patients .
sensory stimulation covering the painful region was obtained ( 50 hz ; 1 ms pulse width ; < 0.6 v ) .
the rf current was delivered at a width of 20 ms at 45 v. the tip temperature was no more than 42c .
patients were observed for 30 minutes after the prf procedure . if no significant complications ( including pain , numbness , bleeding , hematoma , and leg weakness ) were observed , the patient was discharged .
pain intensity , physical functioning , and pain medication were assessed before treatment , at 1 week , at 4 weeks , and at 12 weeks after treatment .
all patients were independently assessed by a nurse who was blinded to the treatment undertaken .
pain intensity was recorded by using a visual analog scale ( vas ) ranging from zero ( no pain ) to ten ( extremely severe pain ) .
pain and physical functioning of the hip were also evaluated by the oxford hip scores ( ohs ) questionnaire , a self - reported 12-item questionnaire.11,12 the range of scores is from 12 to 60 , with a higher score indicating worsening pain and poor function .
pain medication after treatment was assessed using a scale ranging from 0 to 4 ( 0= no medication ; 1= use of paracetamol ; 2= use of nsaids ; 3= use of opiate derivatives ; 4= routinely scheduled opiate derivatives ) .
differences between groups were evaluated using  , fisher s exact test , or mann  whitney u - test , as appropriate .
data were analyzed using spss version 12.0 ( spss inc , chicago , il , usa ) .
patients suffering from chronic hip pain for > 3 months with radiographic osteoarthritis of the hip ( tnnis grades i and ii ) were approached for this study .
patients presented with pain on a range of motions , groin and thigh pain , and limitation of range of motion , especially internal rotation .
patients also underwent various combinations of imaging studies ( plain films , computed tomography , or magnetic resonance imaging ) to diagnose and exclude other causes of pain originating from spine , sacroiliac joint , or other sources . between august 2011 and july 2013
exclusion criteria comprised refusal to participate , extrinsic source of hip pain ( eg , lumbar radiculopathy ) , pain related to bony fracture , avascular necrosis of hip , postsurgical pain , anticoagulation therapy , local infection over buttock and hip , systemic sepsis , allergy to local anesthetics , psychiatric illness , and inability to comprehend pain scoring .
the patients were divided into two groups ( prf and conservative treatment ) according to consent or refusal to undergo prf procedure .
fourteen patients who declined prf because of the possibility of prf complications were managed conservatively .
these patients received exercise programs and medications , including paracetamol , nsaids , and/or narcotic drugs for chronic hip pain .
patients who declined prf were evaluated longitudinally and served as controls . in the prf group , patients received the prf procedure and exercise programs .
patients who received conservative treatment but who still had severe pain could receive prf procedure after 12 weeks treatment if they wanted to cross over .
the techniques for radiofrequency ( rf ) lesioning of the articular branches of the femoral and obturator nerves are described elsewhere.1,9,10 prf was performed under strict sterile conditions in an operating room .
each patient was placed in a supine position , and the skin overlying the operation area was prepared and draped . a standard rf lesion generator ( neurotherm jk 25 t ) was used for the whole procedure .
after administration of local anesthesia ( 2% lidocaine ) , a 22-gauge 10-mm active tip rf cannula ( neurotherm ) 10 cm in length was inserted and advanced toward the articular branches of the obturator and femoral nerves ( figure 1 ) .
denervation of the sensory branches of the obturator and femoral nerves using prf was performed in all the patients .
sensory stimulation covering the painful region was obtained ( 50 hz ; 1 ms pulse width ; < 0.6 v ) .
the rf current was delivered at a width of 20 ms at 45 v. the tip temperature was no more than 42c .
patients were observed for 30 minutes after the prf procedure . if no significant complications ( including pain , numbness , bleeding , hematoma , and leg weakness ) were observed , the patient was discharged .
pain intensity , physical functioning , and pain medication were assessed before treatment , at 1 week , at 4 weeks , and at 12 weeks after treatment .
all patients were independently assessed by a nurse who was blinded to the treatment undertaken .
pain intensity was recorded by using a visual analog scale ( vas ) ranging from zero ( no pain ) to ten ( extremely severe pain ) . pain and physical functioning of the hip
were also evaluated by the oxford hip scores ( ohs ) questionnaire , a self - reported 12-item questionnaire.11,12 the range of scores is from 12 to 60 , with a higher score indicating worsening pain and poor function .
pain medication after treatment was assessed using a scale ranging from 0 to 4 ( 0= no medication ; 1= use of paracetamol ; 2= use of nsaids ; 3= use of opiate derivatives ; 4= routinely scheduled opiate derivatives ) .
descriptive statistics were used to characterize the patients . pre- and posttreatment ranges , means , and standard deviations were calculated .
differences between groups were evaluated using  , fisher s exact test , or mann  whitney u - test , as appropriate .
data were analyzed using spss version 12.0 ( spss inc , chicago , il , usa ) .
patients in both groups were comparable in terms of demographic and baseline characteristics , with no signifi - cant differences between the two groups ( tables 1 and 2 ) .
the flow diagram demonstrates study recruitment , allocation , and follow - up ( figure 2 ) .
after 1 week , changes in vas scores ( p<0.001 ) and revised ohs values ( p<0.001 ) were significantly greater in the prf group than in the conservative group .
the vas scores in the prf group were signifi - cantly lower than those in the conservative group at 1 week ( p<0.001 ) , 4 weeks ( p<0.001 ) , and 12 weeks ( p=0.017 ) .
the ohs values were also lower in the prf group at 1 week ( p<0.001 ) , 4 weeks ( p<0.001 ) , and 12 weeks ( p=0.04 ) .
friedman analysis indicated that for both groups , there were significant differences ( p<0.001 ) in the vas scores after treatment . however , the differences in ohs were only significant in the prf group ( p<0.001 ) .
however , only prf could provide improvement in the physical functioning of hip pain patients .
the pain medication scores were significantly lower in the prf group at 1 week ( p=0.01 ) , 4 weeks ( p=0.007 ) , and 12 weeks ( p=0.01 ) .
thus , prf could provide not only better effect ( 112 weeks ) in terms of pain relief and physical functioning improvement but also less medication requirement .
eight participants in the control group switched to the prf treatment group after 12 weeks .
six ( 75% ) of them had an improvement of > 50% with the pain , whereas two patients ( 25% ) had no improvement .
patients received assessment of adverse events at 1 week , 4 weeks , and 12 weeks after the procedure .
no major complications related with prf were observed , except for one subcutaneous hematoma related to rf needle puncture , which presented for 1 week .
eight participants in the control group switched to the prf treatment group after 12 weeks .
six ( 75% ) of them had an improvement of > 50% with the pain , whereas two patients ( 25% ) had no improvement .
patients received assessment of adverse events at 1 week , 4 weeks , and 12 weeks after the procedure .
no major complications related with prf were observed , except for one subcutaneous hematoma related to rf needle puncture , which presented for 1 week .
the present study compared prf with conservative treatment and demonstrates that at 1 week , 4 weeks , and 12 weeks after treatment initiation , improvements in pain are significantly greater with prf .
improvements of ohs were significantly greater in the prf group at 1 week , 4 weeks , and 12 weeks .
prf provides prompt pain relief , rapid improvements in physical functioning , and a decline in pain medication use .
the sensory nerves supplying the hip joint include the articular branches of the obturator , femoral , and superior gluteal nerves from the sciatic nerve.10 major symptoms of chronic hip pain include groin , thigh , and trochanteric pain .
groin and medial thigh pain often arises from the articular branches of the obturator nerve , whereas trochanteric and lateral thigh pain arises from the articular branches of the femoral nerve.1 in the present study , all the subjects received prf of both articular branches of the femoral and obturator nerves .
lesioning on both nerves provides better pain relief than selecting one nerve according to pain location .
two studies using nerve blocks of the obturator nerve or femoral nerve revealed that each nerve block could only alleviate pain in the arthritic hip for 2 weeks , but the pain subsequently increased to preblock levels.13,14 flanagan et al15 found that intra - articular injection of local anesthetic alone or local anesthetic plus steroid provided short - term pain relief , but no long - term benefit . anesthetic obturator / femoral nerve blocks and intra - articular blocks were effective for hip pain , but long - term benefits were not observed .
the results support the hypothesis that the articular branches of the femoral and obturator nerves are important mediators of hip pain . to obtain longer effects , kawaguchi et
al2 performed crf ablation of sensory branches of the obturator and femoral nerves in 14 patients and found significant pain relief ( at least 50% ) in 12 patients .
the duration of pain relief was 111 months ( mean : 4.2 months ) . in the past 10 years
several studies have reported similar results and pain relief for several months.26 crf in which a constant high temperature ( 60c80c ) is applied to target tissue reduces chronic pain by nerve ablation . it can provide long - lasting pain relief ; however , irreversible damage to neural tissue could occur.16 although crf has been widely used for spinal pain , some have questioned the utility of thermal lesioning in the presence of neuropathic pain as a result of nerve damage.17,18 numbness of the hip related with thermal coagulation during crf and subcutaneous hematoma at the puncture site were the complications.3,4 prf is a new method in rf treatment of pain .
although the mechanism of action is not completely understood , some reports support its long - term efficacy and safety in pain relief.7,8 wu et al1 reported prf of the articular branches of the obturator and femoral nerves in 2 patients with chronic hip pain and demonstrated at least 50% pain relief for 3.5 months . in the present study
, prf provides better pain relief and rapid improvements in physical functioning than conservative treatment .
eight subjects in the conservative treatment group finally received prf treatment after 12 weeks ; and of these , six got > 50% pain relief . exactly
, it produces little tissue destruction but lasting inhibition of evoked synaptic activity.19 prf induces cellular distress , as measured by expression of neuron activation transcription factor-3 , and both c and a delta sensory fibers appear to be selectively targeted by it.20 ultrastructural changes include abnormal membranes and mitochondria morphology and disrupted and disorganized microfilaments and microtubules.21 these changes are greater in c fibers than in a - beta fibers . some studies have examined electrical fields on upregulation of immediate early gene and c - fos.22,23 prf lesioning to the rat dorsal root ganglion was associated with a significant increase of c - fos immunoreactive cells in the dorsal horn of the spinal cord.22,23 the expression of the c - fos gene encourages the formation of preprodynorphin , which is the second rna messenger .
this results in an increased production of endorphin that modulates analgesic action , which may cause a prolonged analgesic effect.24 the present study has some limitations .
a nonrandomized study with patients recruited according to consent or refusal to have prf could have some self - selection bias .
participants agreeing to undergo the prf procedure are more likely to believe in the benefit of the procedure , and this may significantly affect results . however , the nonsignificance of the statistical results in the pretreatment variables and the baseline vas and ohs ( tables 1 and 2 ) values argue against this concern .
however , the observation period for anesthesia for hip pain using prf is no more than 4 months.1 further studies are needed for elucidating the long - term efficacy and safety of prf .
although several studies have reported that prf and crf on sensory branches of the obturator and femoral nerves are effective for chronic hip pain,16 none used a control group .
prf of the articular branches of the femoral and obturator nerves offers a treatment option with good outcomes for patients suffering from chronic hip pain .
when compared with conservative treatment , it offers greater pain relief and can augment physical functioning .
although this study produced promising results , caution is advised in drawing conclusions from this single study .
controlled , randomized investigations with longer observation periods are necessary to further clarify the role of prf in the treatment of chronic hip pain .
 purposechronic hip pain is a common symptom experienced by many people . often , surgery is not an option for patients with multiple comorbidities , and conventional drugs either have many side effects or are ineffective . 
 pulsed radiofrequency ( prf ) is a new method in the treatment of pain . 
 we attempt to compare the efficacy of prf relative to conservative management for chronic hip pain.rpatients and methodsbetween august 2011 and july 2013 , 29 patients with chronic hip pain were divided into two groups ( prf and conservative treatment ) according to consent or refusal to undergo prf procedure . 
 fifteen patients received prf of the articular branches of the femoral and obturator nerves , and 14 patients received conservative treatment . 
 visual analog scale ( vas ) , oxford hip scores ( ohs ) , and pain medications were used for outcome measurement before treatment and at 1 week , 4 weeks , and 12 weeks after treatment.resultsat 1 week , 4 weeks , and 12 weeks after treatment initiation , improvements in vas were significantly greater with prf . 
 improvements in ohs were significantly greater in the prf group at 1 week , 4 weeks , and 12 weeks . 
 patients in the prf group also used less pain medications . 
 eight subjects in the conservative treatment group switched to the prf group after 12 weeks , and six of them had > 50% improvement.conclusionwhen compared with conservative treatment , prf of the articular branches of the femoral and obturator nerves offers greater pain relief for chronic hip pain and can augment physical functioning . 