Ultrasound Therapy (US)

How does it work?

Ultrasound machines conduct an electrical signal through crystals found in the head of the ultrasound probe. The crystals vibrate and create mechanical waves at frequencies outside the range of human hearing (20 hertz to 20000 hertz). This phenomenon is known as the "piezoelectric effect." ¹

As the energy within the sound wave is passed to the material, it will cause oscillation of the particles of that material. Clearly any increase in the molecular vibration in the tissue can result in heat generation, and ultrasound can be used to produce thermal changes in the tissues, though current usage in therapy does not focus on this phenomenon

Non-Thermal effects:
The non-thermal effects of US are now attributed primarily to a combination of CAVITATION and ACOUSTIC STREAMING. The result of the combined effects of stable cavitation and acoustic streaming is that the cell membrane becomes ‘excited’ (up regulates), thus increasing the activity levels of the whole cell. The US energy acts as a trigger for this process, but it is the increased cellular activity which is in effect responsible for the therapeutic benefits of the modality

Courtesy of Prof Tim Watson,
https://www.electrotherapy.org/therapeutic-ultrasound