A chi-square test for heterogeneity was performed. Data synthesis: A total of 2, articles were found. Twenty studies fulfilled the inclusion criteria.
Seven articles assessed the use of IFC on joint pain; 9 articles evaluated the use of IFC on muscle pain; 3 articles evaluated its use on soft tissue shoulder pain; and 1 article examined its use on postoperative pain. Three of the 20 studies were considered to be of high methodological quality, 14 studies were considered to be of moderate methodological quality, and 3 studies were considered to be of poor methodological quality.
Fourteen studies were included in the meta-analysis. As the frequency increases the contraction changes from a twitch to a tetanic contraction. This is stimulation and relaxation of vessel walls, giving a sinusoidal effect. Intensity of current The current is increased until the patient feels tingling.
As accommodation occurs the intensity is increased to the point of muscle stimulation. The duration of treatment varies between 10 - 20 minutes. Electrode placement The patient is positioned comfortably and the skin is prepared for the treatment. It is cleaned and in case of any skin lesion, the area is insulated with petroleum jelly.
Vacuum electrodes or pad electrodes are positioned such that the site for the treatment is accurately located and the two pairs of electrodes are positioned so that the crossing point of the two currents is over or within the lesion.
What are the conditions or symptoms treated by IFT? The main clinical applications for which IFT appears to be used ar Pain Relief in conditions such as causalgia, herpes zoster, neuralgia. Cervical spondylosis. Osteoarthritis of the knee. Ankylosing spondylitis Rheumatoid arthritis. Frozen shoulder. Disc herniation. Spinal canal stenosis. Muscle Stimulation - prevent muscle wastage, re-education, maintain range of motionStress incontinence Reduction of Edema Condition involving the excess collection of watery fluid in the cavities or tissues Muscle injuries Ligamentous injuries.
What are the contraindications of IFT? Select Your City. Related Conditions. Cervical Spondylosis. Rheumatoid Arthritis. Herniated Disk or Sl A total of 2, articles were found. Twenty studies fulfilled the inclusion criteria. Seven articles assessed the use of IFC on joint pain; 9 articles evaluated the use of IFC on muscle pain; 3 articles evaluated its use on soft tissue shoulder pain; and 1 article examined its use on postoperative pain.
Three of the 20 studies were considered to be of high methodological quality, 14 studies were considered to be of moderate methodological quality, and 3 studies were considered to be of poor methodological quality. Fourteen studies were included in the meta-analysis.
Interferential current as a supplement to another intervention seems to be more effective for reducing pain than a control treatment at discharge and more effective than a placebo treatment at the 3-month follow-up. However, it is unknown whether the analgesic effect of IFC is superior to that of the concomitant interventions. Interferential current alone was not significantly better than placebo or other therapy at discharge or follow-up. Results must be considered with caution due to the low number of studies that used IFC alone.
In addition, the heterogeneity across studies and methodological limitations prevent conclusive statements regarding analgesic efficacy. Successful management of musculoskeletal pain is a major challenge in clinical practice. One of the electrotherapeutic techniques used for managing musculoskeletal pain is interferential current therapy IFC. The results of questionnaire surveys in England, 1 Canada, 2 and Australia 3 , 4 have shown that IFC is widely used by diverse clinicians throughout the world.
Interferential current therapy is the application of alternating medium-frequency current 4, Hz amplitude modulated at low frequency 0— Hz. Despite IFC's widespread use, information about it is limited. A review of the literature reveals incomplete and controversial documentation regarding the scientific support of IFC in the management of musculoskeletal pain.
For example, a systematic review about the use of electrotherapy for neck disorders 13 excluded the analysis of IFC. Moreover, much of the IFC information is not written in English, 10 , 14 — 22 and most articles appear to be based on case reports, 23 — 25 clinical studies not including a randomization process, 26 , 27 letters to the editor, 28 , 29 clinical notes, 30 experimental settings, 31 — 37 descriptive studies, 8 , 12 , 38 , 39 or experience in the field 40 , 41 instead of methodologically qualified studies.
Thus, the objective of this systematic review and meta-analysis was to determine the analgesic effectiveness of IFC compared with control, placebo, or other treatment modalities for decreasing pain in patients with painful musculoskeletal conditions.
For details regarding the search terms and combinations, see eAppendix 1 available at ptjournal. The literature search procedure was complemented by manually searching the bibliographies of the identified articles for key authors and journals. Exclusion criteria for this study were: 1 studies based on animal data, 2 studies published in languages other than English, and 3 studies including subjects who were healthy in experimental settings.
Two independent reviewers screened the abstracts of the publications found in the databases. The reviewers analyzed all articles initially selected by the abstract or title for the inclusion and exclusion criteria. In case of discrepancies between reviewers regarding whether a particular article met a criterion, the ratings were compared and the criterion forms were discussed until a consensus was reached. A critical appraisal was conducted to determine the methodological quality of the final selected studies.
We used 7 scales ie, Delphi List, PEDro, Maastricht, Maastricht-Amsterdam List, Bizzini, van Tulder, and Jadad commonly used in the physical therapy field to evaluate the methodological quality of the included studies, compiled in a set of 39 items.
Based on a recent systematic review, 42 no one scale effectively determines the overall methodological quality of individual studies. For this reason, we used all of them in a compiled fashion.
The articles were evaluated on the basis of only the information available in the articles using the critical appraisal sheet eAppendix 2 ; available at ptjournal. For each item listed on the critical appraisal sheet, a score of 1 was given when the item was included in the article, and a score of 0 was given when the item was not included or the information provided by the authors was not sufficient to make a clear statement.
In cases where the study did not consider a particular item, the item was marked as not applicable on the critical appraisal sheet. The scoring for each study was calculated by dividing the number of items included by the number of applicable items. Finally, each study was graded as having low, moderate, or high methodological quality based on how many items from the critical appraisal were met.
The cutoff was determined as follows: 0—0. This criterion was determined a priori to the quality assessment. Similar criteria for cutoffs have been used in correlational studies to determine reference values for quality of association or agreement. The critical appraisal was independently completed by the 2 reviewers, and the results were compared.
Any discrepancies were settled through discussion. Studies investigating similar outcomes and interventions and those providing clear quantitative data were grouped, evaluated for heterogeneity, and pooled, if possible.
When combining outcome data was not possible, narrative, descriptive, and qualitative summaries were completed. In the present study, a meta-analysis was performed to quantify the pooled effect of IFC alone or as an adjunct treatment on pain intensity when compared with placebo, control group, or comparison intervention. Because the pooled effect was based on the results of the VAS or NRS, the mean difference was used to quantify the pooled effect.
RevMan 5. A total of 2, articles were found in the database search. Of these, were selected as potential studies of interest based on abstract review Fig.
After full article review, only 20 studies were deemed to fulfill the initial selection criteria. Seventy-seven studies were rejected after applying the inclusion and exclusion criteria.
The primary reasons for exclusion from the study were: 1 the use of subjects who were healthy in an experimental setting 31 — 37 , 67 — 82 ; 2 descriptive studies in the form of case reports, dissertations, or clinical notes, 8 , 12 , 23 — 25 , 30 , 38 — 41 , 69 , 83 — 96 ; 3 studies not published in the English language 10 , 14 — 22 ; 4 the absence of pain outcomes 97 — ; 5 randomized trial not used 26 , 27 , — ; 6 use of a current other than IFC , ; 7 use of animal data ; and 8 unavailability of the full text of the article.
These studies analyzed the effects of IFC for several diagnoses considered to be either acute or chronic painful conditions. The rest of the articles included the application of IFC as a cointervention along with other therapeutic alternatives such as exercise, 47 , 49 , 53 , 58 — 60 , 62 , 64 — 66 shortwave diathermy, 51 , 59 hot packs, 55 , 60 ice, 58 myofascial release, 55 neuromuscular electrical stimulation, 52 infrared radiation, 51 and ultrasound.
Characteristics of the Studies a. Frequency of 0— Hz for 10 min and 1 30 Hz for 5 min, 3 times a week for 4 wk. IFC: 4 electrodes 2 placed lateromedially and 2 placed anteroposteriorly , frequency of Hz for the first 15 min and 80 Hz for the next 5 min, intensity appreciable sensation. Pain rating was found to be significantly better in the active IFC group than in the placebo group. IFC: 2 electrodes either side of the knee longitudinally , frequency of 80 Hz continuous, intensity strong tingling sensation , min session, 2 sessions a week for 4 wk.
All treatment protocols led to significant reductions in pain and improvement in function. Carrier frequency of 4, Hz, frequency of Hz, Intensity in the tactile sensation, 12 sessions for 4 wk.
Significant improvement in both groups for pain and maximal vertical jaw opening. The results of the critical appraisal for the selected studies are presented in Table 2. Three of the 20 studies were considered to be of high methodological quality, 14 studies were considered to be of moderate quality, and 3 studies were considered to be of poor quality.
Even though the quality of most of the studies was rated as acceptable 17 studies were rated as being of moderate or high quality , there are some points regarding quality that need to be highlighted. Study flaws regarding patient selection were mainly related to description and appropriateness of the randomization procedure and concealment of allocation, with only 9 and 5 of the studies meeting these criteria, respectively. Items related to blinding were not achieved by the majority of the studies.
Only 3 of the studies used a double-blinded design. Methodological Quality of the Studies a. Testing subjects' adherence to intervention or having adequate adherence was another issue that was not accomplished by many studies only 8 and 6 studies, respectively.
Furthermore, adverse effects were reported in only 3 of the studies, and none of the studies provided details of the follow-up period. The outcome measures were not described well in terms of validity, reliability, or responsiveness.
Regarding statistical issues, it was uncertain whether sample size was adequate in 15 of the studies. Intention-to-treat analysis was used only in 11 of the studies. Finally, it also was unclear whether extraneous factors such as equipment calibration or medications during the study could affect the treatment responsiveness for IFC. The effect of IFC has been studied predominantly in patients with chronic painful conditions 16 of 20 trials examined. These conditions included knee osteoarthritis, 47 , 49 , 51 , 52 , 54 , 59 chronic low back pain, 48 , 63 — 65 shoulder soft tissue pain, 53 , 60 , 62 fibromyalgia, 50 chronic jaw pain, 61 and myofascial syndrome pain.
Fourteen studies were included in the meta-analysis Fig. Six studies were excluded for the following reasons: information regarding data variability ie, mean and standard deviation was not present, 58 , 59 the unit of variability included was different than the standard deviation ie, interquartile range, median , 57 , 62 the comparison included in the trial was not relevant for the study's purpose, 48 and the interventions included in the trial were too heterogeneous 51 ie, IFC, infrared radiation, shortwave diathermy, and 2 drugs [sodium hyaluronate and hylan G-F 20].
The 14 selected studies were chosen because they provided complete information on the outcomes evaluated and homogeneity regarding outcome measures. Of these studies, 4 studies 54 , 56 , 61 , 63 addressed the analgesic effect of IFC alone and 10 studies 47 , 49 , 50 , 52 , 53 , 55 , 60 , 64 — 66 evaluated the effect of IFC applied as adjunct in a multimodal treatment protocol. In addition, of these 14 studies, 3 studies 53 , 54 , 66 compared the effectiveness of IFC with a control group, 6 studies 47 , 50 , 54 , 61 , 64 , 65 investigated IFC against placebo, and 7 studies 49 , 52 , 53 , 55 , 56 , 60 , 63 compared IFC with another intervention such as manual therapy or exercise.
Two studies 54 , 61 were included in this comparison. One study 54 measured outcomes at discharge after 4 weeks of therapy, and the other study 61 measured outcomes after 1 week of therapy. One trial 54 studied the effect of IFC on knee osteoarthritis, and the other trial 61 studied the effect of IFC on temporomandibular joint pain. One study 54 was rated of moderate methodological quality, and the other study 61 was rated of poor quality.
The pooled mean difference MD obtained for this analysis was 1. These results indicate that IFC alone was not significantly better than placebo at discharge. Forest plot of comparison: interferential current therapy IFC alone versus placebo treatment on pain intensity at 1 week and 4 weeks data presented as change scores.
Two studies 56 , 63 were included in this comparison. One study 63 measured outcomes at discharge after 2 to 3 weeks of treatment, and the other study 56 measured outcomes after 8 weeks. One trial 56 studied the effect of IFC on acute low back pain, and the other trial 63 studied the effect of IFC on chronic low back pain.
Both studies were of moderate methodological quality. In this comparison, both studies agreed that IFC was not significantly better than manual therapy or traction and massage Fig. These results indicate that IFC alone was not significantly better than any of the comparisons at discharge from therapy.
Forest plot of comparison: interferential current therapy IFC alone versus comparison treatment on pain intensity at 3 weeks and 8 weeks data presented as change scores.
Three studies 53 , 54 , 66 were included in this comparison. Two studies 53 , 54 used a 4-week discharge period, and one study 66 used a one-day discharge period. One trial 54 studied the effect of IFC on knee osteoarthritis, another trial 53 studied the effect of IFC on frozen shoulder, and the third trial 66 studied the effect of IFC on acute low back pain.
Two studies included in this comparison were of moderate methodological quality, 53 , 54 and one study was considered to be of high quality. The pooled MD obtained for this analysis was 2. Thus, IFC applied as a cointervention was more than 2 points better, as measured with the VAS, in reducing pain intensity when compared with a control group in these conditions.
Forest plot of comparison: interferential current therapy IFC as a supplemental treatment versus control treatment on pain intensity at 1 day and 4 weeks data presented as change scores. Five studies 47 , 50 , 54 , 64 , 65 were included in this comparison. Different times of discharge were used in the studies, ranging from 2 weeks 64 , 65 to 4 weeks.
In this comparison, 3 studies 47 , 50 , 54 of moderate quality tended to significantly favor IFC as a cointervention when compared with placebo. One study 64 of moderate methodological quality tended to significantly favor the placebo group. One study of moderate quality did not favor either IFC as a cointervention or placebo Fig. This finding indicates that although IFC as a cointervention was statistically significantly better than a placebo at decreasing pain intensity at discharge in conditions such as osteoarthritis, chronic low back pain, and fibromyalgia, IFC tended to reduce pain in these conditions when compared with a placebo condition.
Forest plot of comparison: interferential current therapy IFC as a supplemental treatment versus placebo treatment on pain intensity at 1-week, 2-week, 4-week, and 3-month follow-ups data presented as change scores.
In this comparison, 2 studies 64 , 65 provided follow-up data 3 months. Thus, an analysis at the 3-month follow-up was performed Fig. The pooled MD obtained for this analysis was 1. The 2 studies significantly favored IFC when compared with the placebo. This finding indicates that IFC as a cointervention was better than a placebo at decreasing pain intensity at the 3-month follow-up. Five studies 49 , 52 , 53 , 55 , 60 were included in this comparison Fig.
Different times of discharge were used, ranging from 1 day 55 to 4 weeks 49 , 53 , 60 to 2 months. Forest plot of comparison: interferential current therapy IFC as a supplemental treatment versus comparison treatment on pain intensity at 1 day, 2 weeks, 4 weeks, and 2 months data presented as change scores.
One study 55 compared IFC plus hot packs, active range of motion, and myofascial release with 5 different treatment modalities; thus, different analyses were run in order to determine the effect of IFC as a cointervention when compared with all of these modalities sensitivity analysis. We used the MD to pool the data. In this comparison, no clear trend favoring either IFC as a cointervention or the comparison treatments was observed for any of the analyses performed Fig.
The pooled MD obtained for the various analyses was 0. The mean difference indicated that IFC as a cointervention was no better than other conventional interventions such as exercise, transcutaneous electrical nerve stimulation, or ultrasound plus hot packs at decreasing pain intensity at discharge. The results of this meta-analysis indicate that IFC applied alone as an intervention for musculoskeletal pain is not significantly better than placebo or comparison therapy ie, manual therapy, traction, massage at discharge from physical therapy treatment.
We also observed differences in length of treatment ie, 1, 2, 3, and 8 weeks and type of pain ie, acute or chronic , indicating no consensus on optimal treatment parameters, which potentially contributed to the nonsignificance of the results. An important factor in this meta-analysis was the inclusion and analysis of studies including the application of IFC as a cointervention in a multimodal treatment protocol.
This decision was clinically sound because IFC is used mainly as an adjunct treatment. The results of this study indicate that IFC as a cointervention is significantly better than control and placebo for reducing chronic musculoskeletal pain at discharge and at 3 months posttreatment, respectively.
The pooled effect for IFC as a cointervention versus control was 2. According to some authors, this change is considered a clinically meaningful effect for acute painful conditions.
In addition, when IFC as a cointervention was compared with placebo at discharge, there was no statistically significant difference between the groups. Thus, it seems that although IFC applied as a cointervention may have a modest analgesic effect, the magnitude of the effect is not large enough to be considered clinically relevant when compared with placebo or comparison interventions.
Because this is the first meta-analysis looking at the analgesic effect of IFC, direct comparisons cannot be made. In a previous study, Johnson and Martinson concluded that transcutaneous electrical nerve stimulation, used mainly as an isolated intervention, provided significant pain relief when compared with a placebo intervention in a variety of chronic musculoskeletal conditions.
Although methodological differences are present between both meta-analyses, some similarities such as the final sample sizes included, the focus on chronic musculoskeletal conditions, and clinical heterogeneity make the comparison between these 2 meta-analyses worth considering. Some factors regarding IFC treatment may have accounted for the modest effect size observed.
Further research is needed to evaluate the effect of noxious stimulation eg, small-diameter fibers on IFC effectiveness, especially in chronic pain. Additionally, IFC has not been applied using a consistent treatment protocol.
Based on the current evidence, recommendations for optimal dosage when using IFC are not clear. It seems, however, that clinical evidence supports the fact that AMF should not be the most important parameter for clinical decision making.
This fact has been corroborated by recent experimental evidence as well. Although some variations in the number of treatments and the treatment time exist, it seems that 10 to 20 minutes of application for 2 to 4 weeks with a total of 12 sessions is the most common treatment protocol for IFC.
In this systematic review, 16 out of 20 studies evaluated the role of IFC in chronic rather than acute pain. Based on this fact, it seems that IFC has been applied more often in the management of chronic painful conditions.
Interestingly, and apparently in contrast to current clinical practice in which IFC is used mostly for short-term pain relief, this meta-analysis provided information regarding potential positive long-term benefits from IFC. An important safety feature when applying electrotherapy modalities is the report of adverse effects.
Although IFC is considered a safe modality, its application has been associated with local adverse effects such as blisters, burns, bruising, and swelling. Two studies 56 , 60 reported no complications, and one study 52 reported the presence of muscle soreness in one subject.
Reporting adverse effects must be mandatory, not only for the safety of patients, but also for the professional integrity of therapists. Even though the quality of the trials appraised generally was moderate, there are some methodological biases common to these studies that could have had an impact on the results.
Selection bias could have existed, as only 9 trials reported appropriate randomization and only 5 trials reported concealment of allocation. Another potentially important bias was the lack of blinding, especially of the patients 9 studies and assessors 11 studies. The outcome measure for this meta-analysis was pain, which is a subjective outcome and dependent on the subject's report. Trials without appropriate randomization, concealment of allocation, and blinding tend to report an inaccurate treatment effect compared with trials that include these features.
Other potential biases that could have affected the observed effects were the lack of an appropriate sample size only 5 of the trials reported adequate sample size and the inappropriate handling of withdrawals and dropouts only 11 trials used intention-to-treat analysis. Reporting clinical significance of results has become a relevant issue to demonstrate the effectiveness of an intervention. Clinical significance provides the clinician with adequate information regarding the clinical impact of an intervention because it can identify when a meaningful change is produced.
The present study used a compilation of items from all of the scales used in the studies in the physical therapy literature. Although some of the scales used in physical therapy ie, PEDro, Jadad have been validated in some way, our recent analysis of health scales used to evaluate methodological quality determined that none of these scales are adequate for that use alone.
However, further research investigating methodological predictors for determining trial quality in physical therapy is needed. As an isolated treatment, IFC was not significantly better than placebo or other interventions.
Conversely, when included in a multimodal treatment plan, IFC displayed a pain-relieving effect VAS reduction of over 2 points compared with a control condition.
This meta-analysis is the first systematic investigation regarding the pain-reducing effectiveness of IFC on musculoskeletal pain. A comprehensive search was made of all the published research in this area over a wide range of years — In addition, authors were contacted in an attempt to have complete information about the selected studies.
The 20 RCT articles included in this review covered a broad spectrum of acute and chronic musculoskeletal conditions. Interferential current therapy was analyzed as isolated intervention, as well as part of a multimodal treatment plan. In addition, the study provided multiple analyses, including the comparison between IFC and placebo, the comparison between IFC and control, and IFC contrasted to different types of interventions.
A main limitation of this meta-analysis is the presence of clinical heterogeneity in the study population in most of the comparisons, casting some doubt on the validity of our results.
A potential limitation is the omission of non—English-language publications; however, English is considered the primary scientific language. Another important limitation is that this study included only pain as an outcome measure. It would be important to know whether outcomes such as disability or function could have been modified by the application of IFC. Interferential current therapy included in a multimodal treatment plan seems to produce a pain-relieving effect in acute and chronic musculoskeletal painful conditions compared with no treatment or placebo.
Interferential current therapy combined with other interventions was shown to be more effective than placebo application at the 3-month follow-up in subjects with chronic low back pain. However, it is evident that under this scenario, the unique effect of IFC is confounded by the impact of other therapeutic interventions. Moreover, it is still unknown whether the analgesic effect of IFC is superior to that of these concomitant interventions.
When IFC is applied alone, its effect does not differ from placebo or other interventions ie, manual therapy, traction, or massage. However, the small number of trials evaluating the isolated effect of IFC, heterogeneity across studies, and methodological limitations identified in these studies prevent conclusive statements regarding its analgesic efficacy.
Because only 4 studies that evaluated the isolated effect of IFC were identified, and these studies had mixed results, further research examining this issue is needed, ideally in homogeneous clinical samples. Further research also is needed to study the effect of IFC on acute painful conditions.
Also of interest would be the study of the effect of IFC in chronic conditions using a theoretical framework for the selection of parameters associated with suprasegmental analgesic mechanisms ie, noxious stimulus instead of sensory stimulation.
Despite the widespread use of interferential current IFC , information about its clinical effectiveness is limited and controversial.
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