As physical therapists, we pride ourselves on our “hands on” approach with our patients. We are respected in the field of health as having excellent manual skills. However, we may also make the most of electrotherapy modalities as an effective adjunct to our hands on treatment.
The most commonly found electrotherapy machines in physical therapy practices are laser, ultrasound and interferential machines. Laser and ultrasound therapy are explained in detail under their own headings. Here interferential therapy is explained.
Interferential therapy is a type of TENS (Transcutaneous Electrical Nerve Stimulation) which has two alternating currents that are applied to the skin. Interferential machines are set a medium frequency current with controls on the machine to adjust the strength of the current and the type of nerve stimulation required. Either two or four pads are applied around the area that needs to be treated (with either a damp sponge or gel between the pads and the skin). The two alternating currents intersect in between the pads and the result of the interconnecting currents is a new frequency (called a beat frequency) which has the desired effect of either stimulating muscle contraction (when the beat frequency is low) or achieving pain relief (when the beat frequency is higher).
The physical therapist controls the machine and adjusts the current as is needed. The patient will feel a mild to strong tingling sensation over the skin and the treatment usually lasts between 10 and 20 minutes with the patient positioned comfortably throughout. When muscle stimulation is required, the muscle that lies between the pads may twitch or sometimes fully contract depending on how strong the stimulation is.
Inferential therapy has several benefits:
- It can help stimulate a weak muscle by causing it to contract repetitively which will help the muscle regain its function, strength and endurance. This is particularly effective for muscles that have wasted after being immobilized in a cast or following neurologically caused muscle weakness such as with a stroke.
- It is very effective for pain relief. Interferential stimulation of the nerves causes the central nervous system to facilitate the release of endorphins (pain relieving chemicals) into the body.
- It stimulates vasodilation in the blood vessels which results in the removal of inflammatory toxins and thus eases swelling.
Interferential therapy is effective in the treatment of:
- Acute soft tissue/sports injuries
- Muscle spasm
- Musculoskeletal pain including low back pain, knee pain and shoulder pain to name a few.
Before commencing interferential therapy, your physical therapist will first assess you with both a subjective and physical examination to clear you of any contraindications to this type of electrotherapy treatment. Patients with cardiac pacemakers, sensory deficits, deep vein thrombosis or pregnant women cannot have interferential therapy.
If you would like to know more about the benefits of interferential therapy, ask your physical therapist.
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