LAB ACTIVITY: BASIC TECHNIQUES FOR INTERFERENTIAL CURRENT
The requirements for production of classical - true IFC are two electric circuits of AC with different
frequencies AND a quadpolar arrangement of the four electrodes. Where these two currents cross
(interfere) in the tissues, a new and different current may be created within the target tissues. This new,
endogenous current is called interferential (interference) current (IF or IFC).
The contraindications & precautions for IFC are the same as those for other forms of electric stimulation
RECOMMENDATIONS FOR PAIN CONTROL / REDUCTION
General Considerations for each treatment approach:
1. Clinical treatment time: 15-20; can be combined with heat or ice. Technically, there is no limit on Rx
time and longer Rx times should result in improved pain control due to endogenous opiate release.
Technique I – for Acute Pain
The following two approaches are recommended for treatment of conditions in which acute pain is
present. Each IFC method is applied at a sensory to low motor response level of amplitude. The
best approach for any given patient is to try both methods during the first IFC treatment to determine
which is most effective. Note: Both methods include a scanning beat frequency to delay neural
accommodation
Method 1: IFC static (no vector) with a scanning high beat frequency (often 80-150 on
most IFC units, but those numbers are NOT known to be superior)
Method 2: IFC with vector and a scanning high beat frequency
NOTE: Trying both methods during one treatment should take just a few minutes each to assess the
patient's preference and make any adjustments in electrode placement and amplitude. Use the
remaining time to treat with the parameters that were the most effective.
QUESTIONS: What is the potential clinical value of scanning the beat frequency?
What is the potential clinical value of vectoring the current?
Technique II – for Chronic Pain
The following two approaches are recommended for treatment of chronic pain conditions. Each IFC
method is applied at a strong, mildly uncomfortable but tolerable, level of amplitude. A motor
response is typical also. The goal is recruitment and overstimulation of A delta and C fibers (pain fibers)
Method 1: IFC static (no vector) with a scanning low beat frequency (often 1-10 on most
IFC units, but those numbers are NOT known to be superior))
Method 2: IFC with vector with a scanning low beat frequency (usually 1-10 on most IFC
units)
Technique III - Premodulated IFC (aka. Bipolar IFC)
Most IFC devices produce an additional current called Premodulated or Bipolar IFC. It is an AC-based
current which is formed by crossing the two AC circuits within the device itself, not within tissues
interferentially. Because the IFC beats are formed within the unit, no expected pattern of IFC occurs
in the tissues. Consider this current to be nothing more than strong current that is loosely
comparable to Russian current.
Premodulated IFC current has a longer phase duration and does not penetrate the skin as well,
compared to classic IFC. Setup for applying this current only requires one channel (2 electrodes, bipolar
stim). Electrodes should be placed so the current will pass on-over & through the painful tissues.
Patient Cases for Pain Management Rx using TENS IFC
1. OUTPATIENT SETTING: Patient is a 33 yo female with a lateral dislocation of the L patella which occurred 2
days ago while working in the yard. The entire knee is moderately effused and the sprained medial
stabilizing tissues are painful along the anteromedial side of the PF joint & knee. Knee extension and
WB/gait are painful. NPRS score today is 5/10
2. SMALL TOWN EMERGENCY DEPT SETTING: Patient is a 63 yo male who suffered an ant-post contusion/crush
injury to the right hand . . . CLASSIC IFC not feasible. COULD TRY PREMOD IFC (BIPOLAR)
3. OUTPATIENT SETTING: Patient is a 49 yo female with bilateral cervical and upper thoracic pain due to long
term occupational and postural stress (clerical work; some lifting). Pain is central as well as immediately
adjacent to the spine (C5-T4 region), and is described as deep, diffuse, and constant (rated 6/10 on NPRS);
some muscle spasm/guarding is palpable and tender.
4. OUTPATIENT SETTING: Patient is a 42 yo male with 5 years of constant (more often than not) central low
back pain (rated 4/10 on VAS); worse with sitting and with movement (rated 6/10 on VAS). Medical dx and
referral is chronic LBP & muscle weakness due to MVA 5 yrs ago. Pain is over L3-5 region and just
adjacent bilaterally, sometimes worse on the left, but typically not much into the musculature.
5. OUTPATIENT SETTING: Patient is a 17 yo male with a healed inversion sprain of the left ankle. Injury occurred 6
weeks ago but was not appropriately treated. Examination reveals chronic edema, severe capsular stiffness
and loss of ROM. Aggressive, painful manual therapy is needed.
6. OUTPATIENT SETTING: Patient is a 56 yo female who’s status is “post-manipulation under anesthesia for R.
adhesive capsulitis (frozen shoulder),” performed 36 hours ago by an orthopedist. Some joint swelling is
present and the shoulder is tender to palpation. All active & passive motions are limited by pain. The joint
ROM obtained during the manipulation (breaking capsular adhesions) must be maintained, despite the pain.
7. HOME / WORK SETTING: You have a contusion injury to the L 1st (big) toe…. CLASSIC IFC NOT VERY
FEASIBLE; COULD TRY PREMOD IFC
8. OUTPATIENT SETTING: Patient is a 40 yo female who is 2 days post R. thigh contusion (specifically over the
vastus lateralis [VL]) from a blunt force trauma during a MVA. Exam reveals moderate superficial tenderness
over the VL, a small, harder area of hematoma, and the presence of painful and tender VL muscle spasm
which is impairing ambulation and knee AROM.
9. OUTPATIENT SETTING: Patient is a 34 yo female with L anterior & posterior medial shinsplints (myositis &
periostitis) on the L after having completed the Little Rock marathon 2 days ago. Exam reveals widespread
tenderness & some edema along the medial & lateral portions of the tibial crest and soreness throughout
the tibialis anterior muscle & with contraction of the deep posterior compartment muscles.
10. HOMEHEALTH SETTING: Patient is a 22 yo male who was in a motorcycle accident 1 day ago which severely
damaged the soft tissue of the R foot….. CLASSIC IFC NOT VERY FEASIBLE; COULD TRY PREMOD IFC
11. PRO BONO (FRIEND/FAMILY) SETTING: Patient is a 51 yo male “weekend warrior” who is a friend of the family.
He has a 2nd degree strain in the belly region of the biceps femoris on the left. The injury occurred during
softball play last night. Exam reveals tenderness to palpation, spasm, some edema, and intense pain (8/10)
when attempting knee flexion, forward trunk flexion (bending) and gait.
12. INDUSTRIAL / WORK SETTING: Patient is a 29 yo male who sustained a L knee hyperextension injury on the
job today. Exam reveals joint effusion with painful AROM and gait. You suspect a capsular sprain, are
treating it symptomatically for a few days as the patient performs light duty (office) activities.
13. OUTPATIENT SETTING: Patient is a 70 yo male with chronic osteoarthritis and long term rotator cuff tears
involving the right shoulder. PROM, AROM & functional use are all limited due to pain. The patient’s
orthopedic surgeon is recommending shoulder joint replacement in the near future Pain is primarily in the
superior and posterior shoulder.