Therapeutic ultrasound uses sound waves to stimulate the repair of soft tissue, relieve pain and create a deep heating effect in the tissue. An ultrasound machine uses an electric current to vibrate a crystal inside the applicator, producing sound waves that penetrate the tissue. It can help wounds heal as well and, with a few exceptions, is a generally safe and effective treatment for many injuries and conditions.
How Therapeutic Ultrasound Works
To treat patients with therapeutic ultrasound, a coupling medium--usually is a water-based gel--is needed. This helps conduct the sound waves from the applicator to the skin and into the tissue. For an irregular body part, such as an elbow, wrists or ankle, performing the treatment with the part submerged in water is suggested. Because the ultrasound waves can produce a heating effect if set to do so, it is important to continuously move the ultrasound applicator head while performing the treatment. It is not safe to leave the ultrasound head in the same place during treatment, as it can cause burns and tissue damage. Therapeutic ultrasound treatments usually last five to 10 minutes, depending on the desired effects.
Indications
There are thermal and non-thermal effects of therapeutic ultrasound in the tissue.
The sound waves cause cavitation and acoustic microstreaming in the tissue, which essentially is a micro-massage for the individual cells. This helps the tissue to heal more efficiently. Both of these are non-thermal effects, which pose no safety concerns.
The thermal effects of therapeutic ultrasound include increased blood flow due to vasodilation, increased tissue flexibility, reduced pain, relief of muscle spasm and increased metabolic activity in the tissue. It is possible to have both thermal and non-thermal effects with the correct machine settings. Thermal effects carry safety concerns, and the correct settings must be used to prevent further injury.
Contraindications
There are conditions in which therapeutic ultrasound is performed with extra safety precautions and times when it is forbidden. In general, therapeutic ultrasound is not safe to be performed if the area has decreased sensation (numbness) or circulation; on the eyes, ears, spine, testes, brain or heart; on the ovaries or abdomen of pregnant women; with acute injuries; on the epiphyseal plates of children; on malignant or cancerous tissue; on open wounds.
The properties of the ultrasound, and the effects it causes can worsen these conditions or cause damage to healthy tissue.
Considerations
Therapeutic ultrasound can be combined with other therapies such as electrical stimulation to help relieve muscle trigger points. It can be used with moist heat packs, to cause a greater increase in tissue temperature, or with cold (and set for non-thermal treatment) to reduce inflammation and promote healing. Occasionally, a topical cream with medication is used as a coupling medium. This is known as phonophoresis and uses the sound waves from the ultrasound applicator to drive the medication into the tissue. To ensure safe application of the medication, the treatment is done by a licensed professional. Phonophoresis is used to treat painful trigger points, tendinitis and bursitis conditions.
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