What Is Therapeutic Ultrasound?
Therapeutic ultrasound is a passive therapy used in physical therapy clinics to treat osteoarthritis. The ultrasound machine contains a crystal that produces ultrasonic waves upon receiving an electrical charge.
These high-frequency sound waves create tiny vibrations that are able to pass in through your skin to reach deeper tissues. These vibrations are virtually undetectable to the person receiving ultrasound treatment. They are also too high a frequency to be heard by human ears.
Ultrasound vibrations can be delivered as pulses or continuous waves. Continuous ultrasound vibrations generate noticeable heat, while pulsed ultrasound vibrations do not. It’s thought that both thermal and non-thermal effects are responsible for any effects these treatments may have.
How Therapeutic Ultrasound Works for Arthritis
Ultrasound works to treat osteoarthritis and other soft tissue damage using either thermal or non-thermal effects.
Ultrasound waves are able to penetrate deep tissue reaching internal structures that other external heat sources (like a heating pad) can’t touch. To be effective, therapeutic ultrasound needs to heat the tissue between 104°F to 113°F for at least 5 minutes.
Ultrasound is also thought to improve cellular function by making microscopic gas bubbles near your injury expand and contract rapidly, a process called cavitation. This expansion and contraction are thought to speed up the healing process in your injured body part.
Effectiveness for Knee and Hip Arthritis
Studies evaluating the effectiveness of therapeutic ultrasound on osteoarthritis have been mixed; some studies found no benefit, and others found some benefits.
A 2019 review of 15 studies with 1,074 patients found therapeutic ultrasound is a safe and effective treatment for osteoarthritis in the knee. The studies show it helps to relieve pain and improve the physical function of the knee.
A 2021 meta-analysis of 14 studies including 1,080 people with knee osteoarthritis found both pulsed and continuous ultrasound are effective and safe for pain relief and functional recovery.
Another study found that low-energy pulsed ultrasound provided about four weeks of pain reduction and improved functioning and quality of life.
Side Effects of Therapeutic Ultrasound
When appropriately performed by a medical professional, therapeutic ultrasound is a safe therapy with virtually no side effects. The treatment uses a hypoallergenic gel that should not cause skin irritation.
The healthcare provider will slowly move the ultrasound wand in a circular motion over the area during the treatment. If the transducer is left in one place for too long, it can cause a superficial skin burn, similar to a sunburn.
A Word From Verywell
Therapeutic ultrasound is a non-invasive treatment that may be effective in treating osteoarthritis in the knee and hip. The therapy appears to be very safe, has few adverse effects, and is relatively inexpensive. There is a wide range of osteoarthritis treatments available. Talk to your healthcare provider to find out if ultrasound therapy for osteoarthritis is right for you.
