Ultrasound, according to Alain-Yvan Belanger, is the most commonly used modality in physical therapy today. Its use dates all the way back to the 1880s. Ultrasound machines generate sound waves that are higher than the frequency we can hear. The effect of these sound waves on the body’s tissues produces a number of benefits.
According to Belanger, the way ultrasound generates heat is through the vibrations caused by the sound waves. When tissues vibrate, this increases friction all the way down to the molecular level, causing the temperature of the targeted tissues to rise. This is a benefit of ultrasound over a traditional hot pack, which cannot penetrate into deeper musculature or joint tissues. Ultrasound heads are available in a variety of frequencies that can target a variety of depths, which gives a skilled therapist the ability to send heat exactly where she wants it to go. Some conditions that may benefit from this deeper heat, according to Belanger, include osteoarthritis and phantom limb pain.
The deep heat generated by ultrasound can help to relax a tense or strained muscle. According to Spine Universe, this can help to minimize muscle spasms and shortening often associated with tension or injury. Spine Universe reports that ultrasound therapy has the added benefit of increasing range of motion.
Ultrasound’s deep heat is thought to have a healing effect on deep tissues. According to Belanger, ultrasound actually affects the metabolism of soft tissue cells. In addition, these cells often become more receptive to healing fluids, which are present in the increased blood flow generated by ultrasound. Because of this, Belanger goes on to report that ultrasound’s healing benefits may be useful in treating surgical wounds and soft tissue lesions.
Scar Tissue Control
Another benefit of ultrasound is its acoustic effect. The waves generated by ultrasound cause tiny vibrations in the cells of the soft tissues. These microvibrations, as Belanger describes them, have an effect on the fibers that form scar tissue. Over time, ultrasound used in this method can actually prevent some scar tissue from forming, and may be able to break some scar tissue down. Examples of success in scar tissue management are episiotomy scars as well as Dupuytren’s contracture, which is caused by excessive scarring in the tissues of the palm. As with its thermal effects, ultrasound used to break up scar tissue can also maintain and increase range of motion.
Some of the pain control from ultrasound comes from the mechanical results of the treatment itself. These include the decreased muscle spasms and muscle tightness as well as tissue healing. However, an added benefit of ultrasound comes not from what it does, but what it can help a physical therapist do. Combining the heating and healing powers of ultrasound prepares muscles for other therapeutic treatments that reduce pain, including stretching and strengthening.
- "Evidence-Based Guide to Therapeutic Physical Agents"; Alain-Yvan Belanger; 2003.
- Spine Universe: Ultrasound: A Common Treatment Used in Physical Therapy