Ultrasound is a method of stimulating the tissue beneath the skin’s surface using very high frequency sound waves, between 800,000 Hz and 2,000,000 Hz, which cannot be heard by humans. Ultrasound Therapy has been utilized by the health care profession to treat conditions such as ligament sprains, muscle sprains, tendonitis, joint inflammation, scar tissue adhesion, rheumatoid arthritis, osteoarthritis, plantar fasciitis, and facet irritation. Benefits of this type of therapy include decreasing healing time due to an increase in blood flow to the affected area, decrease in pain from the reduction of swelling and edema, and by gently massaging muscles, tendons, and ligaments as well as softening scar tissue.
There are generally two types of ultrasound therapy used, thermal and non-thermal. Ultrasound is applied using a transducer or applicator that is in direct contact with the patient’s skin. Gel is used on all surfaces of the head to reduce friction and assist transmission of the ultrasonic waves. Therapeutic ultrasound in physical therapy is alternating compression and rarefaction of sound waves with a frequency of >20,000 cycles/second. Therapeutic ultrasound frequency used is 0.7 to 3.3 MHz. Maximum energy absorption in soft tissue occurs from 2 to 5 cm. Intensity decreases as the waves penetrate deeper. They are absorbed primarily by connective tissue: ligaments, tendons, and fascia.