Interferential therapy

this ppt is about the physiotherapy management for pain
interferential therapy used to treat knee pain, low back ache ,
oedema, muscle spasm

1. INTERFERENTIAL THERAPY
(IFT)
BY
S.CHRISTY SOPNA
PHYSIOTHERAPIST

2. DEFINITION
Interferential therapy is a form of electrical treatment in which two medium
frequency currents are used to produce low frequency effect.
PRINCIPLE: Interferential therapy produces interference effect where two
medium frequency currents cross in the patient’s tissues. An interference
effect is the BEAT FREQUENCY equal to the difference in frequency
between the two currents is produced in the tissues where the two currents
meet.
One of the current is kept at the constant frequency of 4000HZ and other
can be varied between 3900HZ and 4000HZ.

3. INTERFERENTIAL THERAPY

4. ADVANTAGES OF IFT
IFT reduces skin resistance and thus reduces discomfort produced by low
frequency currents
Permits treatment of deep tissues
Low skin impedance for IFT
Medium frequency currents of around 4000HZ,while able to stimulate motor
and sensory nerves encounters a much lower skin impedance
Z= 1/ 2fc
Z= Impedance in ohms
f = frequency in Hertz
C= capacitance of skin in
microfarad

5. INTERFERENCE EFFECT IN TISSUE

6. Terms :
IMPEDANCE: Resistance, capacitance and inductance all these
collectively form the impedance of the circuit. This impedance is a type of
resistance produced by the tissues against any electrical stimulation of low
frequency. Impedance denoted by ‘Z’
ELECTRODES: In Interferential therapy, the flexible electrodes are used
which are taped or bound to skin by vacuum electrodes which use suction
to make contact. Usually four electrodes are used in interferential therapy,
but two electrodes may be used in the treatment.
SWEEP: It is possible to change the frequency, between preset one and
preset one plus additional frequency, continuously in a prefixed pattern
and time, is the sweep.

8. ELECTRODES:
4 electrodes are used in two pairs
The electrode of each pair is placed diagonally opposite one another in
such a way that the interference effect or beat frequency is produced in
the tissues where it is required which may be very deep .
MODE: preselected constant or rhythmic.
RHYTHMIC MODE: indicates that the frequency is swinging continuously
from the lower to higher value and back. The frequency scales available
are:

9. 0-100HZ constant
0-10HZ Rhythmic
90-100HZ Rhythmic
CURRENT is controlled by the therapist and is equal to the sum of the two
separate currents .

11. TYPES OF ELECTRODES
Metal plate electrodes & pads
Quadripolarelectrodes & pads
Suction cup electrodes
Quadripolarsuction cup electrodes

12. APPLICATION
Trigger point –Bipolar technique
Nerve trunk application
Paravertebral application
Muscular application
Transregionalapplication

13. DOSAGE
INTENSITY: Tingling sensation which should not be too uncomfortable or
burning
FREQUENCY:
BEATFREQUENCY STIMULATION
0-5HZ Sympathetic nerve
5-10HZ Parasympatheticnerve
10-50HZ Motor nerve
50-90HZ Sedative & spasmolyticeffect
90-100HZ Analgesic & pain relief

14. CARRIER FREQUENCY: 3900 –4000HZ
TREATMENT TIME: 10 –20 mins
TREATMENT SCHEDULE : twice/day depending on severity and condition
INTENSITY: Comfortable prickling sensation (no discomfort)

15. METHODS OF APPLICATION
STATIC INTERFERENCE
DYNAMIC INTERFERENCE
BIPOLAR INTERFERENCE

16. STATIC INTERFERENCE
Here the area in which IFT is set up remains stationary
This area of static interference gives an appearance of CLOVER LEAF.
It lies to 45°angles to the perpendicular lines from each electrode.
CLOVER LEAF

17. DYNAMIC INTERFERENCE
This is moving the area of interference current in to and fro manner
through 45°
It is obtained by varying the current intensity from 50 to 100%
The dynamic area of interference is also called as vector sweep, vector
scan, rotating vector etc

18. BIPOLAR INTERFERENCE
Here pre modulated IFT are applied through 2 surface electrodes
IFT is generated inside the equipment and it is delivered to the patient
through 2 electrodes
Useful for smaller areas

19. INDICATIONS
Pain
Muscle spasm
Oedema
Hematoma
Chronic ligament lesions
Trigger spots in myofascialsyndrome
Stress incontinence
Pelvic floor training

20. CONTRAINDICATIONS
Arterial disease
DVT (deep vein thrombosis)
Infective conditions
Pregnant uterus
Danger of hemorrhage
Malignant tumor
Pacemaker
During menstruation over abdomen
Open wounds
Unreliable patients
Dermatological conditions
Eyes
Epiphyseal plates in children

21. IFT may be used as a treatment in its own right
IFT is used in combination with other forms of treatment to produce a
comprehensive treatment programme

22. PRECAUTIONS
IFT apparatus must be atleast6 meters away from SWD( short wave
diathermy ) machine
Patient with febrile conditions
Epileptic patients
Over anterior chest wall
Position suction electrode below the level of damage or discomfort

23. HAZARDS
Electric shock
Burns
Increased pain
General malaise
Nausea
Vomitting
Dizziness/fainting
Migraine/headache
Neurological effect
Infection

24. PHYSIOLOGICAL EFFECTS OF IFT
Relief of pain
Motor stimulation
Absorption of exudates