What is ultrasound? | Total Performance Physical Therapy

What is ultrasound?

April 22, 2013

When patients come to physical therapy, they seek assistance and guidance in overcoming their physical ailments so they can live life at it highest quality.  Physical therapists use a variety of treatment options to aid patients.  When coming to physical therapy it is common to receive therapeutic exercise, hands-on therapy, and even education and advice from the therapist.  It is also common to receive what are called modalities or physical agents to help the healing and recovery process.  What are these physical agents?  Physical agents include heat, ice, electrical stimulation, and even laser therapy.  Ultrasound is another commonly used physical agent implemented in countless physical therapy practices.  However, when ultrasound is used the patient sometimes is unaware of the beneficial effects and the reasoning behind its use.  Let’s put this ultrasound issue to rest.

Ultrasound, as the name indicates, uses sound waves at an above audible frequency for a variety of reasons in healthcare, depending on the intensity of the sound waves.  At lower intensities, ultrasound is used as a diagnostic and imaging tool.  This is commonly seen for the imaging of a developing fetus in a pregnant mother.  At very high intensities, ultrasound is used surgically.  This is to say that ultrasound is used as a ‘destructive’ tool in surgery to destroy lesions, tumors, or kidney stones.  At a more middle intensity, ultrasound is used as a therapeutic tool as patients will see in physical therapy.

The ultrasound devices patients see in physical therapy clinics have a safe and therapeutic effect that supports the recovery process.  How does it help?  The ultrasound promotes healing, reduces pain, and heats soft tissue.  I like to think of it as ‘a deep heating agent’.  Something like a hot pack is not able to penetrate deep beneath the skin to heat up the soft tissue (this is not to say that hot packs are bad, just a little different).  The ultrasound beams are able to travel 2.5-5 cm beneath the skin to heat the soft tissue and promote healing thereby decreasing pain.  This depth may not sound like a lot, but it targets the tissues your physical therapist wants to heal.  This is why physical therapists use ultrasound in an injured or stiff area of the body.  Obviously, the longer the ultrasound is used and at a greater intensities, then the greater the thermal effects.

Why does the ultrasound head need to be moved?

A physical therapist is constantly moving the ultrasound head while its in use.  The reasoning behind this is that the physical therapist wants to prevent “hot spots”.  A “hot spot” occurs if the sound head is left still and the sound waves reflect back on one another causing pain.  The physical therapist moves the sound head to prevent a painful sensation from occurring and to have the effect over a larger area.  However, if the sound head is moved too fast, this will limit the heating effect.

Ultrasound Research in Physical Therapy

Besides using ultrasound as a deep heating agent that increases healing and decreases pain there have been some specific conditions where ultrasound has been shown to be especially beneficial in expediting the rehabilitation process.  Research shows that ultrasound is especially beneficial in patients with carpal tunnel syndrome and calcific tendinitis of the shoulder.  It is also shown in the research that ultrasound can be helpful in fracture healing, but the exact biological mechanism behind this is unknown.  If you have one of these conditions, physical therapy and the use of ultrasound will help decrease your pain and symptoms.

In 2002, Busse and others performed a meta-analysis of 6 research articles that aimed to determine if low-intensity pulsed ultrasound had a beneficial effect on fracture healing.  This article was published in the Canadian Medical Association Journal and indicated positive findings.  The results showed a significant difference in the healing time of non-operative closed fractures when ultrasound was used.  The mean difference in healing time was 64 days between people where ultrasound was used versus those that did not use ultrasound.

A systematic review conducted in 2001 by Robertson & Baker and published in the Journal of the American Physical Therapy Association, aimed to determine the effectiveness of ultrasound amongst people seen in physical therapy clinics.  The systematic review looked at ten randomized control trials that used active ultrasound versus placebo ultrasound.  The examination of these 10 research articles revealed ultrasound to be especially effective in patients with calcific tendinitis and carpal tunnel syndrome.  For people with calcific tendinitis, ultrasound decreased calcium deposits and also decreased patient’s pain and symptoms.  For people with carpal tunnel syndrome, ultrasound decreased patient’s pain and symptoms and also increased the functioning of their involved hand.  However, from this research there were no specifications as to the exact ultrasound dosage needed for effectiveness since the dosage varied amongst the articles examined.

These two research studies as well as many others prove the effectiveness and positive impact of ultrasound to treat patient’s pain and symptoms in physical therapy.

If you would like even greater detail about ultrasound or have any questions, visit or call Total Performance Physical Therapy