PT Classroom - A Review of the use of Interferential Current in the Physical Therapy Setting ׀ by Chai Rasavong, MPT, MBA


Interferential current therapy (IFC) is one of many modalities which may be utilized in the physical therapy plan of care to assist with decreasing pain, stimulating muscle, reducing edema and increasing circulation (1, 2). The purpose of IFC therapy is to deliver currents into deeper tissue by overcoming skin impedance (2, 3, 4, 5). To accomplish this feat, it involves the creation of a waveform produced by the interference of two medium frequency sinusoidal, symmetrical, alternating currents at frequencies of several thousand cycles per second which are set at slightly different frequencies (ie. fixed carrier frequency of 4,000 Hz and second adjustable frequency of 4,001-4,400 Hz) (1, 2, 3, 4). These two waveforms are delivered through two sets of electrodes through separate channels in the same stimulator (3). These electrodes are oriented in a quadripolar orientation which allows for the two alternating currents to intersect (3, 4). As a result of the currents intersecting they interfere and create the desired signal frequency (3, 4). The IFC stimulation is thus concentrated at the point of intersection between the electrodes (See Figure 1 below).


Figure 1 - Intersecting medium frequency alternating currents producing an interferential current between two crossed pairs of electrodes (2, 3,6)

Despite its wide use in the physical therapy setting, studies regarding its efficacy vary and are somewhat lacking (2, 5). In a study by Johnson et al. (2) they compared the analgesic effects of IFC and TENS on experimentally induced ischemic pain in otherwise pain-free subjects using a modified version of the submaximal-effort tourniquet technique. They concluded that there were no differences in the magnitude of analgesia between IFC and TENS. They did find that IFC reduced pain intensity to a greater extent than sham electrotherapy.

In a systematic review and meta-analysis conducted by Fuentes et al. (5), they analyzed the available information regarding the efficacy of IFC in the management of musculoskeletal pain. They discovered a total of 2,235 articles but were only able to utilize 14 studies which met their inclusion requirements. From their meta-analysis, they concluded that IFC as a supplement to another intervention seems to be more effective for reducing pain than a control treatment at discharge and more effective than placebo treatment at the 3 month follow up. However, they were unable to conclude if the analgesic effect of IFC is superior to that of the concomitant interventions. They also found that IFC alone was not significantly better than placebo or other therapy at discharge or follow up.

Additional research is required when examining the use of IFC as an isolated treatment as only four studies with mixed results were found that met this criteria (5). However, studies do support that IFC as a supplement to another physical therapy intervention is effective for reducing pain (5). This in turn, does open up the need to conduct studies comparing IFC to the various other physical therapy interventions. 


Last revised: October 20, 2011
by Chai Rasavong, MPT, MBA


1) Goats GC, Inferential Current Therapy. Br. J. Sports Med. 1990;24:87-92.
2) Johnson MI, Tabasam G. An investigation Into the Analgesic Effects of Interferential Currents and Transcutaneous Electrical Nerve Stimulation on Experimentally Induced Ischemic Pain in Otherwise Pain-Free Volunteers. Physical Therapy. 2003;83(3):208-223.
3) Cameron M. Physical Agents in Rehabilitation: From Research to Practice. Saunders. 2003;222-223.
4) Robinson AJ, Snyder-Mackler L. Clinical Electrophysiology: Electrotherapy and Electrophysiologic Testing - Second Edition. Williams & Wilkins. 1995;65-67.
5) Fuentes JP, et al. Effectiveness of Interferential Current Therapy in the Management of Musculoskeletal Pain: A Systematic Review and Meta-Analysis. Physical Therapy. 2010;90(9):1219-1238.
6) May H-U, Hansjurgens A: Nemectrodyn Model 7 Manual of Nemectron GmbH, Daimlerstr. 15, Karlsruche/Germany, 1984.

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