Therapeutic Ultrasound - a Quick Overview

Therapeutic ultrasound           

 is a method of stimulating tissue beneath the skin's surface using sound waves. The sound waves are very high frequency, typically between 800,000Hz and 2,000,000Hz, and can penetrate up to 4 inches below the surface of your skin. The sound cannot be heard by humans or animals (humans can only hear sounds up to about 20,000Hz). This very high frequency sound affects very small molecules and cells in the body, and actually causes them to move around.

The way ultrasound waves are transferred into the body is a function of many factors. The frequency of the ultrasound waves is actually opposite to how deep they will penetrate the body. For example, a 1MHz ultrasound will penetrate about 4 inches below the skin, whereas a 2MHz ultrasound unit will only penetrate about 2 inches. While a low frequency means deeper penetration, using too low of a frequency will mean that the waves are too wide to properly move the molecules. For therapeutic applications, 1MHz is the optimal frequency for both effectiveness and penetration.

 Power output is another significant factor. It is measured in watts per square centimeter. The higher the power, the more energy is transferred into the body. If too high a power output is used and an ultrasound unit is left sitting still on the body, it is possible to burn the tissue beneath the skin. While several professional ultrasound machines are capable of these high powers, your medical practitioner will typically use a lower power setting, below 1 watt per centimeter squared. More power is not necessarily better. Though some therapists may use higher powers to speed up ultrasound treatments, it is actually more effective to use a lower power setting for a longer period of time to achieve the optimal healing effect.

The power output rating is often broken down into two separate units: peak intensity and average intensity. Peak intensity can be thought of as how tall the sound waves being sent into your body are. The waves need to be large enough to affect the tissue and provide the desired therapeutic effect. At the same time, your body tissue needs breaks between groups of waves to cool down. So, Ultrasound machines actually send the waves in "pulses" (groups,) giving your body a vibrate-rest-vibrate-rest effect. The average intensity is a measure of how much energy is transferred over a period of vibrate-rest cycles.

When applied directly to the skin, an ultrasound device cannot effectively transfer the sound waves into the body. To make it work properly, a conductive medium is required - ultrasound gel. The gel simply makes it possible for the sound waves to travel from the unit head into your body. Ultrasound treatments without gel is ineffective, and can damage the ultrasound unit.Ultrasound machines provide a Total Power Output rating. High power units are typically used with large applicator heads to treat larger areas of the body. The important measurement part of ultrasound is the watts per square centimeter mentioned above, not the total unit power. Again, it is more effective to treat the affected area more frequently and for longer periods of time, using a lower power setting.

What Does it Do?

The heating and massaging effects of Therapeutic Ultrasound have two primary benefits. First, it increases blood flow to the treated area, which speeds the healing process. Second, it reduces swelling and edema, which are the main sources of pain.

Ultrasound can also be used to administer therapeutic medicines into the body, through a process called phonophoresis. In such a case, there are 3 benefits to a treatment, the first two from the massaging effect of ultrasound discussed above, and the third from phonophoretically administering the medication. Ultrasound treatments with Phonophoresis are rapidly becoming more popular than Ultrasound Therapy alone, due to the added benefits.

For most injuries and ailments, a cycle of ultrasound therapy should optimally consist of 5-10 minute treatments, repeated 2-3 times per day for the duration of the healing period- this routine will mean fast, efficient healing, allowing you to get back to your normal life without being in pain. This surprises many people who have gone for single treatments in clincs only 2 or 3 times each week. The clinic approach, while providing the benefits of ultrasound therapy, simply become too expensive and too inconvenient.

When you have a tendinitis or tenosynovitis injury, the area becomes inflamed as the damaged tissue cells release toxins. These toxins cause the injured area to be tender to touch, red, and sore to move. As the toxins and damaged cells accumulate, blood vessels become blocked and fluid gathers... resulting in swelling and pain. This is very much like the effect a dam has on a river - the flow is stopped and the fluid just builds up.

In most cases of a tear, strain, pull, or cartilage degeneration, scar tissue begins to form at the injury site, binding your tissues together abnormally.

Unlike healthy tissue that works like a stretchy elastic band, scar tissue is tough and inflexible. Most of us know of someone that just can't seem to recover from a soft tissue injury - a good example is a runner that has injured their achilles tendon: the injury stops hurting so they start running again, and the scar tissue from the old injury just prevent the achilles from flexing properly, so they keep straining it time after time. In fact, 90% of runners that have injured their achilles will reinjure their achilles again... this is what scar tissue can do - it turns a short term injury into a long term recurring injury.