Ultrasound is a treatment that has been used by physiotherapists since the 1940s. Ultrasound is applied using a round bar or probe that is in direct contact with the patient's skin. Ultrasonic gel is applied to all surfaces of the head to reduce friction and aid in the transmission of ultrasound. The frequency range of the therapeutic ultrasound is approximately 0.8-1.0 MHz.

The wave is produced by the piezoelectric effect caused by crystal vibrations in the rod/probe head. Sound waves that pass through the skin cause local tissue vibrations. This vibration or cavitation can cause deep heating locally, but usually the patient does not feel the thermal sensation. Ultrasound can be pulsed rather than continuously transmitted without the need for a heating effect, such as fresh injury from acute inflammation.

In addition to the potential heating effect, ultrasound can produce many effects. It has been shown to cause tissue relaxation, increased local blood flow and scar tissue destruction. The effect of increased local blood flow can be used to help reduce local swelling and chronic inflammation, and, according to some studies, promote fracture healing. The intensity or power density of the ultrasound can be adjusted depending on the desired effect. The power density is greater [in watts per square centimeter and is often used for the target of scar tissue damage].

Ultrasound can also be used to achieve ultrasound penetration therapy. This is a non-invasive method of administering drugs to subcutaneous tissue; it is suitable for patients who are uncomfortable with injections. Using this technique, ultrasonic energy forces the drug through the skin. Cortisone, which is used to reduce inflammation, is one of the more commonly used substances delivered in this manner.

Typical ultrasound treatment takes 3-5 minutes. In the case where scar tissue destruction is the target, this treatment time can be longer. The head of the ultrasound probe maintains constant motion during treatment. If left unchanged, the patient should not feel any discomfort. If the probe is held in place for more than a few seconds, it will produce an accumulation of acoustic energy, which may become uncomfortable. Interestingly, severe pain may be felt if there is even a very small break in the bone in the area close to the surface. This happens when the sound waves are trapped between the two parts of the rest and accumulate until they become painful. In this way, ultrasound can often be used as a fairly accurate tool for diagnosing minor fractures that may not be apparent on X-rays.

Some conditions of ultrasound therapy include tendinitis [or tendonitis if you wish], non-acute joint swelling, muscle spasms, and even Peyronie's disease [to break scar tissue]. Ultrasound contraindications include topical malignancies, metal implants under the treated area, local acute infections, vascular abnormalities, and directly in the abdomen of pregnant women. Ultrasound is directly applied to the active osteophyte area [growth plate] in children. The spinal cord or eyes of the laminectomy area, the skull or the testicle are also contraindicated.

Ultrasound and physical therapy was originally published on Spring