Therapeutic ultrasound is a treatment commonly used in physical therapy to provide deep heating to soft tissues in the body. These tissues include muscles, tendons, joints, and ligaments.
Ultrasound in physical therapy is different than diagnostic ultrasound. With the latter, healthcare providers useultrasound to see the inside of the body. For example, diagnostic ultrasound lets healthcare providers check on a fetus during pregnancy.
This article explains how therapeutic ultrasound works and when it's used.
What Is Therapeutic Ultrasound?
Therapeutic ultrasound is used to heat tissues and introduce energy into the body.
Deep Heating Effects
Ultrasound can provide deep heating to soft tissue structures in the body. Deep heating tendons, muscles, or ligaments could have the following benefits:
- Increase circulation to tissues
- Speed the healing process
- Decrease pain
- Increase elasticity
Deep heating can increase the "stretchiness" of muscles and tendons that may be tight.
If you have shoulder pain and have been diagnosed with a frozen shoulder, your physical therapist (PT) may use ultrasound. This therapy is usually done before performing range of motion exercises because it can help improve the ability of your shoulder to stretch.
Click Play to Learn More About the Use of Therapeutic Ultrasound
This video has been medically reviewed by Laura Campedelli, PT, DPT.
Non-Thermal Effects (Cavitation)
In addition to heat, ultrasound introduces energy into the body. This energy causes microscopic gas bubbles around your tissues to expand and contract rapidly, a process called cavitation.
It is theorized that the expansion and contraction of these bubbles help speed cellular processes and help injured tissue heal faster.
When cavitation is unstable, it can be dangerous to your body's tissues. So, your physical therapist will work to ensure that the cavitation during therapy is stable.
Therapeutic ultrasound uses heat and energy to increase circulation, decrease pain, increase flexibility, and speed healing.
How Does Ultrasound Work?
Inside your physical therapist's ultrasound unit is a small crystal. When an electrical charge hits this crystal, it vibrates rapidly, creating piezoelectric waves (an electric charge that accumulates in some solid materials). These waves emit from the ultrasound sound head as ultrasound waves.
During treatment, the ultrasound wave then enters into your injured tissues. This exposure to ultrasonic waves increases blood flow and cavitation, leading to the theorized benefits of the treatment.
When Is It Used?
PTs may use therapeutic ultrasound to treat some injuries and chronic pain.
Usually, PTs treat orthopedic (musculoskeletal) injuries with ultrasound. These may include:
- Bursitis (inflammation in the fluid-filled sacs along joints)
- Muscle strains and tears
- Frozen shoulder
- Sprains and ligament injuries
- Joint contracture or tightness
Generally speaking, any soft-tissue injury in the body may be a candidate for ultrasound therapy. For example, your physical therapist may use ultrasound for low back pain, neck pain, rotator cuff tears, knee meniscus tears, or ankle sprains.
There is also some evidence that you may benefit from ultrasound treatments if you have chronic pain. It is thought that the ultrasound waves help improve tissue extensibility and circulation, leading to increased mobility and, ultimately, decreased pain.
PTs use therapeutic ultrasound for specific soft-tissue injuries, including joint pain, muscle strains and tears, and ligament injuries. In addition, they sometimes use it for chronic pain.
Ultrasound Therapy for Chronic Pain
What to Expect
Ultrasound uses amachine that has an ultrasound transducer (sound head). First, a PT applies a small amount of gel to the particular body part; then, your physical therapist slowly moves the sound head in a small circular direction on your body.
What Ultrasound Feels Like
While receiving an ultrasound treatment, you will most likely not feel anything happening, except perhaps a slight warming sensation or tingling around the treatment area.
If the ultrasound sound head is left in place on your skin and not moved in a circular direction, you may experience pain. If this occurs, tell your physical therapist right away.
The therapist may change various settings of the ultrasound unit to control the ultrasound wave's penetration depth or change the ultrasound's intensity. In addition, they may use different settings during various stages of healing.
Alternative methods of ultrasound application are available if the body part is bony and bumpy or if there's an open wound. (The ultrasound gel and sound head may harbor bacteria that can enter the wound.) These include:
- Direct contact (most commonly used method)
- Water immersion
- Bladder technique
Ultrasound + Medication
Your PT may use ultrasound gel combined with a topical medication to help treat inflammation around the soft tissue in the body. This process is called phonophoresis.
While there is evidence that ultrasound waves help deliver the medicated gel to the injured tissues, most published studies indicate that this treatment may be ineffective.
Therapeutic ultrasound does not result in many bodily sensations, other than the feeling of the ultrasound wand against your skin. Your PT may use various settings or different application methods depending on your situation.
There are some instances where you should not use ultrasound at all. These contraindications to ultrasound may include:
- Over open wounds
- Over metastatic lesions (cancer that has spread) or any active areas of cancer
- Over areas of decreased sensation
- Over parts of the body with metal implants, like in a total knee replacement or lumbar fusion
- Near or over a pacemaker
- Around the eyes, breasts, or sexual organs
- Over fractured bones
- Near or over an implanted electrical stimulation device
- Overactive epiphyses in children
- Over an area of acute infection
Does Evidence Support Its Use?
Many studies have found that ultrasound offers little benefit to the overall outcome of physical therapy. In fact, in a series of papers published in Physical Therapy Journal in 2001, ultrasound received a grade of "C" (no benefit demonstrated) for certain conditions, including:
- Knee pain
- Low back pain
- Neck pain
In addition, a 2014 study in the American Journal of Physical Medicine and Rehabilitation examined the effect of ultrasound on pain and function in patients with knee osteoarthritis. The researchers found no difference in knee function and pain with rehab using ultrasound, no ultrasound, and sham (fake) ultrasound.
Is It Right For You?
Some argue that ultrasound can harm your physical therapy by needlessly prolonging your care. So, if your physical therapist is providing ultrasound for you, you may question if it is really necessary as part of your overall rehab program.
Ultrasound may not work for everyone, but it may be worth a try if you have chronic, ongoing pain. Some people may suggest that the benefit of ultrasound for chronic pain is due to the placebo effect. But, if it gives you relief, then it is the proper treatment for you.
Ultrasound is a passive treatment. In other words, you can't provide the therapy yourself; you are a passive receiver of the ultrasound.If your physical therapist uses ultrasound during your treatment, make sure you are engaged in an active exercise program to help improve your functional mobility.
Exercise and active involvement should always be the main components of your rehab program.
Therapeutic ultrasound is different from diagnostic ultrasound. PTs use it to treat some injuries and chronic pain. Evidence is mixed on the purported benefits of therapeutic ultrasound. However, since it is low-risk for most people, it may be worth trying, especially if you experience chronic pain.
A Word From Verywell
If your physical therapist suggests ultrasound, be sure to ask about why it's needed and possible risks. Also, be sure to perform an active self-care exercise program in the PT clinic and at home. If you are actively engaged in your rehabilitation, you can ensure that you have a safe and rapid recovery back to normal function.
Frequently Asked Questions
Why is ultrasound used in physical therapy?
Therapeutic ultrasound is used in physical therapy to help heal soft tissue like muscles, tendons, and ligaments. Ultrasound technology involves applying electricity to a special crystal. This process creates piezoelectric waves that emit from the ultrasound wand. The waves deep heat the soft tissue, increasing blood flow to the area to promote healing.
What does therapeutic ultrasound feel like?(Video) An Overview of Ultrasound Therapy
You typically won’t feel much during ultrasound therapy. The physical therapist will apply a gel then rub the wand against the skin in the area of the injury. You may start to feel a warm sensation, or you may not feel anything at all. Tell your PT if you experience any discomfort during the treatment.
Does therapeutic ultrasound help relieve pain?
Possibly, but only as part of a physical therapy regimen that includes stretching and strengthening exercises. On its own, there is no demonstrated benefit of therapeutic ultrasound for knee pain, low back pain, or neck pain.
Is therapeutic ultrasound safe?
Yes, therapeutic ultrasound is a safe, FDA-approved treatment. There are no known harmful side effects from a therapeutic ultrasound performed correctly by a physical therapist.
What do physical therapists use ultrasound for? ›
Ultrasound is a sound wave with a frequency above the range of human hearing. Physical therapists use ultrasound to help treat musculoskeletal injuries and improve healing after auto accidents, work accidents and related incidents. Ultrasound physical therapy can help to: Reduce pain.Does ultrasound help heal tendons? ›
There is strong supporting evidence from animal studies about the positive effects of ultrasound on tendon healing. In vitro studies have also demonstrated that ultrasound can stimulate cell migration, proliferation, and collagen synthesis of tendon cells that may benefit tendon healing.Does ultrasound reduce inflammation? ›
Background: Low-intensity ultrasound (LIUS) was shown to be beneficial in mitigating inflammation and facilitating tissue repair in various pathologies.How often can you use ultrasound for pain? ›
Commonly the treatment lasts 5 to 10 minutes, and it's typically not performed more than once per day.Does ultrasound treatment help arthritis? ›
Ultrasound therapy can be useful in repair cartilage damage caused by arthritis. A study (Low Intensity Ultrasound as a Supporter of Cartilage Regeneration...) found that ultrasound therapy allows oxygen to be delivered to the injured tissue of the joints facilitating tissue repair.What type of patients use ultrasound therapy? ›
1 As such, ultrasound therapy is often used to treat injuries and muscle spasms, as well as chronic issues like neck or back pain. Typically a physical therapist, a professional who helps individuals manage pain and improve mobility, administers this treatment.Does ultrasound help nerve pain? ›
Mechanical stress may be used to stimulate peripheral nerve regeneration during neurorehabilitation. Therapeutic ultrasound (US) is a promising treatment that promotes nerve regeneration [8–12].What are the negative effects of ultrasound in treatment? ›
Mechanical therapeutic ultrasounds may potentially cause internal bleeding or scarring, depending on the duration of exposure. Although unlikely, a “microplosion” can occur as a result of cavitation therapeutic ultrasounds, which may damage cellular activity.
Ultrasound therapy is one of the most commonly used physical modalities in osteoarthritis treatment. İt has a deep heating effect and increases tissue regeneration, blood flow and metabolic effects while reducing the inflammation and relaxing the muscles.Does ultrasound help tight muscles? ›
Ultrasound is a passive modality, meaning a treatment your physcial therapist administers. It is a supplement to the primary treatment (eg, therapeutic stretching, exercise). Ultrasound can help relax tight muscles that are sore, and warms muscles and soft tissues, which increases circulation that helps healing.
Does ultrasound help heal muscles? ›
Promote Tissue Healing – Ultrasound not only improves your muscles and joint range of motion, but can aid in the healing of wounded tissues. The metabolism of the cells in the tissue are affected by ultrasound. The vibration produced by the ultrasound can help prevent scar tissue from forming.Does ultrasound help soft tissue damage? ›
Therapeutic ultrasound (TUS) is used for the treatment of musculoskeletal disorders, including acute soft tissue injuries, overuse syndromes, as well as chronic orthopedic and rheumatologic conditions.What injuries would you use ultrasound for? ›
- Back pain.
- Carpal tunnel syndrome.
- Frozen shoulder.
- Joint pain and tightness.
- Knee pain.
Ultrasound imaging uses sound waves to produce pictures of the inside of the body. It helps diagnose the causes of pain, swelling and infection in the body's internal organs and to examine an unborn child (fetus) in pregnant women. In infants, doctors commonly use ultrasound to evaluate the brain, hips, and spine. .What injuries can ultrasound be used for? ›
- Ligament sprains.
- Muscle strains.
- Tennis and golfers elbow.
- Plantar fasciitis.
- Scar tissue adhesions.
- Bruising and contusion.
Some common conditions that ultrasound helps treat include, but are not limited to:
- Frozen shoulder.
- Muscle spasms.
- Sprains, strains, and tears.