The high frequency acoustic vibrations of ultrasound are used by physical therapists to produce both thermal and non-thermal effects. The deep heating capability of ultrasound reaches into the muscles to increase collagen elasticity, reduce muscle spasm and pain, and improve blood flow. Ultrasound has also been shown to stimulate protein synthesis, tissue regeneration, and bone healing. A special application of ultrasound is phonophoresis, a method of driving medication from the surface of the skin into underlying tissues. Reinold, who uses phonophoresis for applying anti-inflammatories like hydrocortisone and salicylates, anesthetics like lidocaine, and counterirritants like menthol.
Most therapists use phonophoresis despite inconclusive research results.
Iontophoresis This modality uses small electric currents to carry ions of soluble salts through the skin and into the underlying tissues. Iontophoresis has been found to decrease inflammation, reduce scar formation, help wounds heal, and break down calcium deposits using acetic acid. Electrical Stimulation A variety of electrical stimulation modalities are used in physical therapy clinics, and some devices are portable and worn at home. When muscles cannot contract voluntarily, electrical stimulation can help strengthen them and prevent disuse atrophy. This modality is also used for muscle re-education following surgery or nerve injury.