Interferential for Osteoarthritic Knee Pain

   Interferential therapy has been used for the management of inflammatory pain conditions and is gaining popularity.(1)  The use of interferential for osteoarthritic knee pain  is gaining acceptance over the use of NSAIDs (Nonsteroidal anti-inflammatory drugs)  due to it’s simplicity and lack of any relevant side effects.  The benefit of interferential for acute pain situations may be more demonstrable than it’s use for chronic pain, which is a symptomatic diagnosis rather than a causative agent of pain.  Now it is possible for a patient to self treat from their home or office so it should not be unexpected that the use of interferential for osteoarthritic pain may experience an upsurge in new non-drug applications for pain relief and greater mobility, pain free.

    Two studies ( 2) (3) demonstrated that the use of interferential therapy, IFC treatment,  done twice daily can provide pain relief between 1 week to as long as 6 months.   The importance of those studies is to compare a safe therapy, IFC, to the use of NSAIDS and the effect of the long term relief gained by interferential over the very short duration of relief from drugs.  The pain relief from interferential is immediate and provides a strong analgesia for the patient so resumption of daily activities is immediate and pain free.

     The study highlites  the major strength of interferential therapy providing carryover pain relief for the patient without having to do daily or even weekly treatments.

   For information on how to use the Infrex Plus For Osteoarthritis watch this video.

Studies this article taken from:

            (1) Payne R. Limitations of NSAIDs for pain management: toxicity or lack of efficacy? The Journal of Pain. 2000;1:14-18.

           (2) Shafshak TS, el-Sheshai AM, Soltan HE. Personality traits in the mechanisms of interferential therapy for osteoarthritic knee pain.- Arch Phys Med Rehabil. 1991;72:579-581.

           (3) Quirk A, Newman R, Newman K. An evaluation of interferential therapy, shortwave - Physiotherapy. 1985;71:55-57.



Why Combine Tens and Interferential In One Device?

( See Tens Interferential video below)

   Tens and interferential units are both used to block the pain signals along sensory nerve routes and often are used as natural and effective pain management.  Interferential Stimulation differs from TENS because it allows a deeper penetration of efficacious electrical current in  the tissue with more comfort (compliance) and increased circulation.    ' For example, at a frequency of 4,000 Hz (Interferential unit) capacitive skin resistance is eighty (80) times lower than with a frequency of 50 Hz (in the TENS range).


TENS (Transcutaneous Electrical Nerve Stimulation) was designed to stimulate sensory nerve endings in order to decrease the perception of pain. The stimulus blocks pain signals passing along the nerves to the central nervous system. There are many articles that also say TENS will produce excess production of natural pain killers which will control pain but in practice this methodology with TENS rarely is efficacious. TENS blocks pain signals to the brain/spinal cord. TENS stimulation is characterized by biphasic (positive/negative) balanced charges and user selectable pulse width and pulse rate.



Interferential therapy ( IF/ IFC)  is often described as ‘deep TENS’. Interferential therapy is two high frequencies of 4,000 cycles per channel, overlapping,  resulting in 8,000+ pulses per second in the affected area.  That enables the electrical currents to penetrate deeper into the tissues.  The extra frequency allows the frequency over 8,000,(1- 150) the benefit of low frequency stimulation without the uncomfortable effects of TENS.   Interferential therapy offers not only pain relief, but also contributes to acceleration in healing, increased blood flow and edema reduction.

    The basic goal of interferential current therapy is to give a pleasant sensation during treatment and achieve deeper tissue penetration. The uncomfortable sensation felt by many patients using TENS is due to the resistance of the skin to the passing electrical currents. The level of discomfort is inversely proportional to the frequency of stimulation. Hence, the lower the frequency applied, the greater is the discomfort felt. Interferential current therapy uses two medium frequencies applied at the same time in such way that their paths cross and interfere with each other. The interference between them leads to changes producing modulated frequency that has the same therapeutic effects as low frequency stimulation, but without the normal side effects of unpleasant sensation or discomfort.   

     Interferential therapy is safe and has no side effects. While the interferential therapy is very effective, it causes a minimum skin sensation and the level of discomfort related to the electrical stimulation. 


Conditions that respond to TENS & Interferential include the following:


Rheumatoid Arthritis,


Post Amputation Pain, - Phantom Limb Pain

Back Pain,




Sports Injuries,


Skeletal Pains,

Muscle Aches,

Cancer Pain,

Menstrual Pain,

Labour Pain,

Tension – Migraine

Travel Sickness.



Insurance Reimbursable


     Tens has been recognized as efficacious and the rent and purchase paid by almost all major insurance companies for decades, including Medicare (HCFA), when used for chronic pain.  Medicare will pay for an interferential treatment in a health facility but does not pay for the rental/purchase of an interferential unit.  Many patients have not had the money to pay out of pocket for an interferential unit even though the benefits are obtained in the clinical setting . In certain instances a patient may have coverage for “DME”, durable medical equipment, such as wheelchairs, potty seats, canes, crutches, and walkers.  If the patient has DME coverage then in almost all situations Interferential may be covered.


    The combination of TENS and IFC in one unit now means when the unit is prescribed for chronic pain that even Medicare will cover it.  The new combination IFC/TENS device with both modalities will open up new treatment parameters for patients now that an IFC unit can be rented or purchased by a patient.


New Treatment for Reflex Sympathetic Dystrophy (RSD)

    Reflex sympathetic dystrophy (RSD) is a type of neuropathic pain that manifests itself as a complex regional pain syndrome.  It is a chronic condition, meaning it can last a lifetime. 

    Reflex Sympathetic Dystrophy is a complicated nervous system disorder characterized by a severe burning pain, usually localized, but may spread, and which is accompanied by abnormal changes in the bone and skin in the area.  Excessive sweating, tissue swelling, and an extreme sensitivity to touch are also common characteristics. RSD  is diagnosed when there is pain, swelling or change in color or increase or decrease of blood flow in the particular affected area. It is three times more likely to occur in women than men


   Symptoms may include constant chronic burning pain (stabbing, sharp accompanied by tingling sensation).  The painful area may be hot or cold and very sensitive to touch.  Often the patient experiences difficulty in sleeping, emotional distress, and fatigue or general weakness.   The patient may experience long term wasting of the muscles in the extremities due to inactivity brought on by pain.

 Traditional Therapy

     Treatment modalities for RSD have included various medications, physical therapy, sympathetic nerve blocks, placement of spinal cord stimulators, as well as the use of a morphine pump.  The preferred method to treat RSD includes sympathetic block and physical therapy incorporating the use of electrotherapy which historically has been through use of a TENS unit.  Tens units have not helped significantly with RSD because the electrode placement is difficult and there is no carryover relief from Tens.   Treatment is directed at the relief of pain so the patient can begin more progressive rehabilitation caused by the disease itself.  Stimulation of the spinal cord and nerve endings by electrical current is done to relieve pain. 

 New Therapy Treatment

     Others who have used TENS have found that although there is significant pain relief during the initial phase, there is a drop off after several weeks of therapy.   One of the problems with TENS is the modality itself does not have what is called “carryover” relief, i.e. when the unit is turned off, the pain comes back.  Interferential has been used for relief and has the benefit of extending relief post-treatment.   Because the units are large, expensive, and require greater amounts of electrical energy, the patient would have to go to a facility for treatments.  

     Today that is no longer the case. The interferential unit is portable, powered by AC adapter or batteries for home use.   The patient can self treat as needed. The carryover relief period seems to extend for longer periods of time as more treatments are done.  Some patients may have pain relief for only a few hours or days after treatment. From limited observations with the new interferential units, it appears that the carryover pain relief is extending.

      Interferential is the most used form of clinical electrotherapy for chronic pain in the world.   And now, the Infrex Plus is available for home use.                                      

  Aromatherapy For Asthma


   Asthma is classified into two types but both types have the common physical denominator of bronchial tube constriction resulting in loss of breath and difficulty in breathing.   Essential oils,  such as bergamot  capable of producing relaxation,  and bronchodilatation are indicated in many formulations. 

  The bronchodilator will be an oil that can act on the nerve endings surrounding the bronchial tubes in the lung.  The mechanism is to have the oil interact with the beta-2 receptors.

Diagnostic  Indications for the Use Of Interferential Therapy

    Interferential therapy has been around for more than 50 years,  being used historically for many different pathologies.  Many of the past uses were administered by licensed medical personnel and the most novel approaches to new disease pathologies were often done in Europe.  The physiotherapy profession in Europe was instrumental in finding ways interferential could be used for existing illnesses.

    Some of the applications are:

1.  Treatment of circulatory disorders

2.  Edema reduction

3.  Constipation

4.  Urinary incontinency

5.  Wound healing

6.  Healing broken bones ( non-union fractures)

7.  Stopping muscle spasms

8.  Chronic as well as acute pain 

9.  Asthma

10.  Increased blood flow

11.  Multiple Sclerosis

12. Peripheral Neuropathy

     One of the main benefits of interferential is that the stimulus itself overcomes the resistance of the skin so the subcutaneous tissues can be reached.  There are methods one can use to decrease the resistance and thus increase the efficacy of the treatment.
Prior to treatment one may....

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*  For external use

* Safety of stimulation during pregnancy or delivery has not been yet established

* Do not stimulate the eye area

* The therapy may be ineffective for pain of central origin

*  Stimulation should not be applied over the neck or mouth.  Severe spasm of the laryngeal and pharyngeal muscles may occur
   and the contraindications may be strong enough to close the airway or cause breathing difficulty.

*  Stimulation is a symptomatic treatment and as such suppresses the sensation of pain, which otherwise serves as a protective mechanism.

*  This device should be kept out of the reach of children.


* Caution should be used for patients with suspected or diagnosed heart problems and epilepsy

*  Some patients may experience skin irritation or hypersensitivity due to the electrical stimulation or electrical conductive medium

*  Electrode placement and stimulation settings should be based on the guidance of the prescribing practitioner

*  This device should be used only with the leads and electrodes recommended for use by the manufacturer.

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