Ultrasound is applied using a round-headed wand or probe that is put in direct contact with the patient’s skin. Therapeutic ultrasound is in the frequency range of about 0.8-3.0 MHz. The waves are generated by a piezoelectric effect caused by the vibration of crystals within the head of the wand/probe. The sound waves that pass through the skin cause a vibration of the local tissues.
Its effects are an increase in tissue relaxation, local blood flow, and scar tissue breakdown. The effect of the increase in local blood flow can be used to help reduce local swelling and chronic inflammation, and, according to some studies, promote bone fracture healing. It can also be used to achieve phonophoresis.