1. Interferential Current (IFC)
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

2. IFC Waveform Precursors
2 electrical circuits (channels) of AC
Medium Frequency AC (1, ,000 Hz)
One Carrier (fixed) frequency AC
One Variable frequency AC
Example: Hz / Hz. Diff = Beat Freq

3. Why Medium Frequency AC?
Comfortable
With AC, higher freq = short phase width = lower impedance
Possibility of neural block

4. Production of IFC (theoretical, endogenous current)
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

5. IFC production - in a uniform medium (think 3-D)
Clover-leaf Pattern of IFC
Each circuit equal amplitude at a 90 degree angle to each other.
Vector addition

6. Parameters to be used Beat Frequency & Amplitude.
Options with Beat Freq:
Fixed vs Scanning Freq. (WHY?)
Vectoring / Sweeping of IFC “oscillation of the cloverleaf”
Purpose
Physics

7. IFC in the Tissues: Reality ??
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).

8. Application & Rx Guidelines
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
Premodulated IFC (Bipolar)
IFC produced in the unit & delivered thru 1 channel, not as comfortable but can put on & over; convenient

9. IFC – sample applications

10. Ant knee: IFC (left) vs Tens (right) Gastroc: IFC (right) vs Tens (left)

11. Hamstring: IFC (right) vs Tens (left)

12. Lateral Elbow: IFC (left) vs Tens (right)