Dr. Roger Allen, PhD, PT
Purpose: Interferential current (IFC) is widely used in conjunction with other therapies to manage musculoskeletal pain. While previous systematic reviews have found a lack of studies examining the independent treatment effects of IFC, this study reviews the isolated effects of IFC compared to a control group. The purpose of this study is to determine if IFC is an effective modality for treating musculoskeletal pain.
Number of Subjects: Ten peer-reviewed journal articles, representing a total of 898 participants
Materials/Methods: CINAHL, PubMed, Cochrane Library, PEDro , SportDISCUS and CENTRAL were searched between November 2016 and February 2017 with the following terms: interferential current, interferential therapy, interferential electrical stimulation, pain, and analgesia. Articles met inclusion criteria if they were randomized controlled trials (RCT) that had IFC as an intervention and a measurement of pain as an outcome measure. Studies were excluded if they were duplications, if they had a publication date prior to 2009, if they were not published in English, if they had thermal induced pain in healthy subjects, if the effects of IFC were not tested in isolation of other treatments, or if no form of a control group was used.
Results: The initial search yielded 285 results with 10 eligible studies adhering to inclusion and exclusion criteria, published from 2011-2016. Populations were comprised of healthy participants and patients with the following diagnoses: carpal tunnel syndrome, shoulder hemiplegia, chronic low back pain, and knee osteoarthritis. Outcome measures included subjective pain reports such as the visual analog scale (VAS) or the pain intensity numeric rating scale (PI-NRS), objective physiological measurements such as pain-free ROM or a 15 meter walk test, pain behavior assessments such as medication use, and functional outcome measures such as the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). These 10 studies were analyzed with a PEDro scale: scores ranged from five through nine, with a mean value of seven. All nine RCTs that used a carrier frequency of 4,000 Hz reported a positive effect of IFC: seven reported a reduction in a measure of pain and two reported a decrease in use of pain medication. One RCT reported no significant effect of IFC when using a carrier frequency of 2,000 Hz. Four of the ten RCTs evaluated long term effects: three RCTs found positive lasting benefits, while one RCT found no significant long term improvements.
Conclusions: In conclusion, the evidence supports the use of IFC in the treatment of musculoskeletal pain. More research is needed to determine the most effective parameters and evaluate long term effectiveness.
Clinical Relevance: IFC is an effective tool as an in-clinic palliative intervention for the short term management of musculoskeletal pain, which may improve functional outcomes and reduce patient use of pain medications.
University of Puget Sound
Skipper, Ginny SPT; Maissy, Sarah SPT; and Allen, Roger PhD, PT, "Effect of Interferential Current in the Management of Musculoskeletal Pain: A Systematic Review" (2018). Physical Therapy Research Symposium. 47.