Interferential Current (IFC)
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A unique use of kilohertz AC waveform
“endogenous production of the IFC”
Emphasis on use for pain control & some
limited NMES applications
Anecdotal support - tissue healing &
increase circulation via autonomic
stimulation
Hx - Dr. Hans Nemec 1950s in Austria;
popularized in US in late 70s / early 80s;
remains popular
IFC Waveform Precursors
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2 electrical circuits (channels) of AC
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Medium Frequency AC (1,000 - 10,000 Hz)
One Carrier (fixed) frequency AC
One Variable frequency AC
Example: 5000 Hz / 5100 Hz. Diff = Beat Freq
Why Medium Frequency AC?
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Comfortable
– With AC, higher freq = short phase
width = lower impedance
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Possibility of neural block
Production of IFC
(theoretical, endogenous current)
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Interference of 2 MFACs within the tissues results in
the endogenous IFC
Beat Frequency: Variable freq – Carrier freq = Beat
Waveform interaction (on an oscilloscope);
Benefit: IFC can be 2X amp of MFACs but doesn’t
have to penetrate skin
IFC production - in a
uniform medium (think 3-D)
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Clover-leaf Pattern of IFC
 Each circuit equal amplitude at a 90
degree angle to each other.
 Vector addition
Parameters to be used
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Beat Frequency & Amplitude.
 Options with Beat Freq:
– Fixed vs Scanning Freq. (WHY?)
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Vectoring / Sweeping of IFC
“oscillation of the cloverleaf”
– Purpose
– Physics
IFC in the Tissues: Reality ??
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Clover-Leaf pattern not realistic in human tissue
 Valid theoretical concept in uniform medium
 IFC technology is complex, but the mechanisms
of pain control are largely the same as TENS.
 Potentially better pain control
– increased depth of current
– comfort with stimulation
– typically a clinical Rx only (PT applied & supervised,
combined w/ heat or cold).
Application & Rx Guidelines
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Treatment of an area of pain (joint OR soft tissue)
with IFC. Quadpolar setup, X marks the spot.
– Acute Pain: High Freq (>50), Sensory to Low Motor Amp
– Chronic Pain: Low Freq (<10), Motor to Noxious Amp
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Premodulated IFC (Bipolar)
– IFC produced in the unit & delivered thru 1 channel, not
as comfortable but can put on & over; convenient
IFC – sample applications
Ant knee: IFC (left) vs Tens (right)
Gastroc: IFC (right) vs Tens (left)
Hamstring: IFC (right) vs Tens (left)
Lateral Elbow: IFC (left) vs Tens (right)