What is therapeutic ultrasound?
If you have had physical therapy, you may have experienced therapeutic ultrasound (TUS) as part of your treatment. Although they both use soundwave energy, therapeutic ultrasound is not the same as diagnostic ultrasound. Therapeutic ultrasound uses sound energy at frequencies greater than 20,000 Hz to affect biologic tissues in different ways, depending upon what settings are used. It is a non-invasive, non-painful modality we can use in conjunction with other therapeutic modalities to address a wide variety of orthopedic and soft tissue problems.
How does it work?
TUS units produce sound waves that are emitted by the transducer. These are basically mechanical pressure waves. As these pressure waves penetrate through tissue, their energy is absorbed and converted into kinetic energy. This causes a chain reaction of vibrating molecules that affect the cells in the body in different ways. If continuous sound waves are used, then heat is produced and thermal effects occur. Heat produced by ultrasound is focused and penetrates much deeper into tissues than topical heat sources, like hot packs. If pulsed sound waves are used, then mechanical or non-thermal effects occur. The non-thermal effects modify cellular functions and membrane permeability, assisting with tissue repair and reduction of swelling.
TUS provides deep heating to muscles, tendons and ligaments. This improves the flexibility of the tissues and is ideal to do prior to therapeutic stretching or exercises. For patients whose joints are temporarily immobilized due to injury or surgery, TUS may also reduce the development of muscle contracture. The non-thermal effects of TUS can also improve joint range of motion and help to reduce the amount of muscle atrophy during joint immobilization.
TUS Improves Tissue Flexibility and Joint Range of Motion
TUS Promotes Tissue Healing and Protects Tissues for Further Damage
TUS improves blood flow and microcirculation to damaged tissues. This helps healing by allowing more nutrients to be delivered to the tissues while waste products are removed. TUS also promotes the formation of new blood vessels to the treated areas as well as granulation tissue formation, which is important in the healing process. It also hastens wound contraction by stimulating collagen production. Some studies indicate that TUS may also have a beneficial effect on nerve regeneration and healing of articular cartilage.
TUS Reduces Pain
When providing thermal (heating) effects, TUS can reduce pain in a variety of musculoskeletal disorders including osteoarthritis and pain from myofascial trigger points. The warmth increases blood flow to the affected tissues which helps to remove pain mediators, nerve conduction is impacted and muscle spasms are reduced. The non-thermal or mechanical effects of TUS also reduce pain by altering cell membrane permeability in such a way that inflammation is reduced. There is also evidence that TUS may have a positive impact on the central nervous system pathways of processing pain.
What effects does therapeutic ultrasound (TUS) have on the body?
