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1. INTERFENETIAL THERAPY
Prof. Dr. M. Rajesh, PT, M.P.T(cardio), BCRC
TRINITY MISSION AND MEDICAL FOUNDATION
MADURAI

2. INTRODUCTION
 Interferential therapy is a form of electrical treatment in which
two medium frequency currents are used to produce a low
frequency effects.
 Medium frequency currents of around 4000Hz, while able to
stimulate motor and sensory nerves, encounter a much lower
skin-impedence.
 IFT used to applying deeper tissues.

3. PRINCIPLES
Beat frequency
 Skin resistance depends on frequency.
Résistance inversely proportional to
frequency
Z = I/2FC
Z – skin resistance in ohms
F – frequency in Hz
C – capacitance of the skin in
microfarads

4. Interference effect
 Two medium frequency currents interfered in heterodyned to
make beat frequency
 The beat frequency can modulate
Principle of IFT effect
 Frequency range is limiting values, by changing one channel
frequency in IFT.

5. VARIATIONS OF INTERFERENCE
Scale
 1 -100Hz constant
 1 -10Hz rhythmic
 90 -100Hz rhythmic
 [ 10 sec – go up; 5 sec – come down]
Frequency swing by two control knobs
 1-100Hz (Bosch)
 0 –150Hz (Endomed)

6. Skin current compensations
 It is achieved by electrode placements.
 Electrodes close together – resistance is decreased
Interferential vector system
 The vector mode advantage is specific area at any depth, it can
be treated with pulse low frequency stimulation.

7. Electrokinesy
 It is one of the IFT application technique, which is using a glove
type electrode worn by physiotherapist. It is apply with 4000Hz,
carrying in low frequency modulation(50Hz) applied with glove
electrode.
Surge
 It has varying surged upto 2-12 mins.

8. IFT with Galvanism(DC)
 The IFT is combine with DC and select suitable pole.
Stereodynamic IFT
 In this technique, IFT applied with three pair of electrode or
STAR electrode

9. PHYSIOLOGICAL EFFECTS OF
IFT
The effects depends on
 Selection frequency range
 Rhythmic or constant frequency swings
 Intensity
 Accuracy of electrode placement
 Circulation and neurological functions
 Underlying pathophysiology

10. 100Hz constant-
 It is produce fine vibrations on sensory nerve endings – used of
analgesic effect
 Tingling sensation – decrease pain (applied for upto 10-15
mins)
 Direct stimulation – inhibition of the sympathetic system(use to
treat causalgic pain, reflex sympathetic dystrophy)
 Increase vasodilation

11. 1-10Hz constant-
 Effects on muscular contraction
 Less sensory stimulation
 Greater depth of muscle stimulation

12. 1-100Hz rhythmic-
 Fine vibrations of the ions leads to facilitate the ion movments
through cell membrane.
 It made increase venous return and lymphatic flow.
90-100Hz rhythmic
 Analgesic effect – especially neuralgic pain (e.g. Brachial
neuralgia)

13. 1-10Hz rhythmic-
 Stimulatory effect on motor and underlying tissues
 Increase vasodilatory effect
 Vigorous pumping effect (help to start absorbtion of exudates)
Electrokinesy (50Hz with 4000Hz current)
 Useful in pain and muscle spasm conditions with application 2-3
mins

14. INDICATIONS
 Pain
 Muscle spasm
 Oedema
 Haematoma(on first 24 hours used with ice packs)
 Chronic ligamentous lesions
 Trigger spots in myofascial syndrome
 Stress incontinence (treat wih vaccum electrodes; 1-100Hz
rhythmic with 15 mins application; electrode positioned in lower
abdomen just above pubis and inside of thigh on upper
posterior medial side)
 Delayed union and Sudek’s atrophy – apply with 15-20 mins/day
for 2-3 weeks

15. CONTRAINDICATIONS
 Arterial disease
 DVT or thrombo-phlebitis
 Infective conditions
 Pregnancy
 Danger of haemorrhage
 Malignant tumours
 Artificial pacemaker
 During menstruation
 Febile condition
 Large size open wound
 Unreliable patients
 Dermatological conditions

16. DOSAGE
Intensity (Depends on size of electrode)
 Low doses – not noticeable
 Medium doses – just noticeable
 High doses – clearly experienced, vigorous, pleasant sensation
 Very high does – strong, vigorous, unpleasant sensation

17. Frequency and duration
Analgesic effect
 Acute pain – 90-100Hz rhythmic, medium doses, 10 mins
application
 Chronic pain – 100Hz constant, medium doses, 10 mins
application
Oedema
 100Hz constant, medium dose, 10 mins
 1-100Hz rhythmic, medium dose, 10 mins


18. Tenacious exudates
 1-100Hz rhythmic, high dose, 10mins
 1-10Hz rhythmic, high dose, 10mins
Pain due to sympathetic dysfunction
 100Hz constant, medium dose, 10mins
 90-100Hz rhythmic, medium dose, 10mins

19. Stimulation of weak muscles with innervated
 1-10Hz rhythmic, high dose, 5-15mins
Posterior root ganglion irritation
 90-100Hz rhythmic, low dose, 10-15mins

20. Parametritis (pelvic inflammation)
 100Hz constant, medium dose, 15mins
 1-100Hz rhythmic, medium dose, 10mins
Phatom pain
 100Hz constant or 90-100Hz rhythmic, high dose, 10mins

21. METHODS OF APPLICATION
IFT applied with different type of electrodes
 Metal plate electrode and pads
 Quadripolar plate electrode
 Suction cup electrodes
 Quadripolar suction cup electrodes
 Quadripolar probe electrode

24. TECHNIQUES OF APPLIATION
 Patient should be comfortable position
 Skin is prepared as for low frequency stimulation(thoroughly
washed and apply petroleum jelly if any skin lesions)
 Site of treatment area is accurately located
 Patient should be instructed about treatment, type current,
sensation and effects
 Set treatment frequency
 Rise intensity
 Get the patient verbal feedback about the sensation and rise the
intensity with regular interval
 After the completion of the session, get feedback about the
treatment
 Maintain patients record and fix next appointment.

25. DANGERS
 Burns – due to bare metal electrode, electrode close together,
increase intensity, and decrease moisture in the pads
 Haematoma (commonly seen in suction cup electrodes)
 Poor results – due to faulty position, incorrect frequency and
dose.

26. ADVANTAGES
 Large doses doesn’t produce chemical burns
 Decreased sensation is not a contraindication
 Metal implant is not a contraindication(IFT is apply with caution
in this case)
 Treatment with referred pain is effectively treated.

27. THANK YOU
Prof. Dr. M. RAJESH, PT,M.P.T(cardio),B.C.R.C
TRINITY MISSIOIN AND MEDICAL FOUNDATION
MADURAI.
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