Ultrasound Therapy for Tendonitis

Tendonitis is a painful condition caused by the overuse of a specific tendon, commonly occurring in the shoulder, elbow, and heel. Symptoms of tendonitis include pain, tenderness, swelling, and stiffness. Treatment options for tendonitis vary, and one potential option for patients is ultrasound therapy, which utilises high-frequency sound waves to heat deep tissue and promote tendon healing. Research on ultrasound therapy has mixed results but has been shown to provide pain relief for tendonitis and aid rehabilitation and recovery. 

Overview

What is tendonitis?

Tendonitis (sometimes spelt tendinitis) is a condition where the tendons, the thick, fibrous cords that attach our muscles to our bones, become inflamed or swollen. This inflammation causes pain and tenderness outside of a joint. Injury to a tendon can cause micro-tears, and if left untreated, these tears may exacerbate over time.¹

Prevalence of tendonitis

Tendonitis impacts between two and five per cent of the general population. If you are a runner or an athlete, those odds increase. Studies have shown that about 10% of runners develop Achilles tendinopathy (overuse of the Achilles tendon connecting the heel and calf) each year. What is even more striking is that almost half of all sports injuries are tendon injuries.¹⁰ These findings demonstrate the need for treatment options for tendonitis. 

What is ultrasound therapy for tendonitis?

Ultrasound therapy (or therapeutic ultrasound) for tendonitis is a treatment option that uses high-frequency sound waves to reduce pain and promote healing. Much like diagnostic ultrasound scans, ultrasound therapy uses a hand-held device called a transducer coupled with a conducting gel that is applied to the skin. A physical therapist will move the transducer in a circular motion over the injured or painful tendons. Ultrasound therapy for tendonitis works by warming the tendons, muscles, and other tissues to accelerate healing through improved blood flow.² 

Understanding tendonitis in more detail

Causes and risk factors

Tendonitis is generally caused by overuse of a particular tendon, often through sports, exercise, or repetitive work. Risk factors for developing tendonitis include ageing and health conditions such as diabetes and rheumatoid arthritis, as tendons lose elasticity and become more susceptible to injury.. Tendonitis can affect any tendon in the body but most commonly affects those near joints such as: 

• Shoulder (rotator cuff tendonitis)
• Elbow (lateral epicondylitis, commonly known as tennis elbow)
• Wrist
• Thumb (De Quervain’s tenosynovitis)
• Knee
• Heel (Achilles tendonitis)

Symptoms and diagnosis

Common symptoms of tendonitis include: 

• Pain (may be worse at night or with movement or activity) 
• Tenderness
• Swelling
• Stiffness (especially in the morning)
• A crackling sound when you move the tendon (crepitus)

A healthcare provider will perform a physical exam to diagnose tendonitis and ask questions about your symptoms, medical history, and normal daily activities. Some doctors may order complementary imaging such as an MRI or X-Ray to rule out a tendon rupture or other injury. 

It is important to seek early intervention and adjust your daily activity if you think that you have tendonitis. Repetitive strain on an injured tendon can lead to the development of chronic tendinosis (the chronic state of tendonitis).¹ Minor tears in the tendon can pose the risk of further damage and cause complete tear or rupture of the tendon. If the tendon is completely torn and does not respond to treatment, surgery may be required to repair the tendon and stimulate natural healing. 

Basics of ultrasound therapy

What is ultrasound?

You may be familiar with ultrasound as an imaging method that uses high-frequency sound waves to produce images within your body. The frequencies of sound used in ultrasound are too high for humans to hear at between 2–20 Megahertz.  Therapeutic ultrasound also uses these high frequency sound waves but to increase blood flow by heating tissue rather than produce an image.

How does ultrasound treat tendonitis?

Using ultrasound therapeutically began in the 1930s utilising the mechanism of tissue heating.³ This technology is non-invasive, meaning there is no breaking of the skin or entering of the body. By focusing the acoustic intensity towards the tendon, the sound waves can generate heat leading to increased blood flow, reduced swelling and pain relief. This is the thermal mechanism of action of ultrasound therapy and occurs due to the absorption of the sound waves by tissues. Ultrasound therapy also has a non-thermal mechanism of action due to cavitation, where the sound waves cause tissues to vibrate and form microscopic bubbles that stimulate a self-healing inflammatory response.¹

Effectiveness of ultrasound therapy

Review of clinical trials

Studies have reported mixed results concerning the effectiveness of ultrasound therapy for tendonitis. Overall, ultrasound therapies show potential as an alternative therapy with lower risk side-effects than more invasive methods like surgery.¹ Most of the variance is related to different treatment types, measurements, and reporting from studies. One study compared ultrasound therapy to a control group (no treatment) in people with shoulder tendonitis.⁴ The results showed that those receiving ultrasound therapy saw significantly more clinical improvement and the researchers concluded that ultrasound therapy was an effective treatment for tendonitis, due to the mechanism of increased blood flow.⁵ 

Comparison with other treatment modalities

A common at-home treatment for tendonitis is the RICE method— Rest, Ice, Compression and Elevation.⁶ Other common treatments for tendonitis include:

• Physiotherapy
• Steroid injections
• Pain medication
• Surgery
• Dry needling

Ultrasound therapy can be implemented alongside these treatments to complement recovery from tendonitis. 

Ultrasound therapy sessions

Frequency of ultrasound

Depending on the location of the affected tendon, there are different frequencies and intensities of ultrasound. Generally, low-frequency waves can reach deeper tendons while higher-frequency waves can focus on more superficial tendons. Low-frequency ultrasound between 1–3MHz (Megahertz) is the most commonly used intensity for tendonitis.⁶ 

Duration of therapy sessions

Ultrasound therapy sessions may last anywhere from 2 to 30 minutes. Often a course of ultrasound therapy is required over a period of weeks or months, depending on the severity and chronic nature of the tendon injury.⁶  

What happens at an ultrasound therapy appointment?

Doctors are the primary care provider for therapeutic ultrasounds, while support staff often assist in monitoring patients and equipment.⁷ Trained physiotherapists may also recommend and perform ultrasound therapy alongside exercises. There have been instances of ultrasound therapy being used without proper training or device certification.⁸ At an ultrasound therapy appointment:

1. The healthcare provider will inspect the device before beginning treatment.⁷ 
2. The provider will check the area for infection, open wounds, or burns around the affected tendon.⁷ If these are present, the treatment may not be able to go ahead.
3. The treatment will begin when the provider applies the hand-held transducer with coupling gel to the surrounding area, moving in a circular motion over the painful or injured anatomy.² Ultrasound therapy itself should not be painful but be aware if you start to feel heat increasing underneath the applicator.
4. Treatment will last for several minutes depending on your injury. 

Home ultrasound devices

Portable ultrasound therapy machines are available on the market for at-home ultrasound therapy. Home ultrasound kits range in price from a few hundred to a few thousand pounds. When purchasing a home ultrasound device, it is important to consider the frequency of the ultrasound waves that it delivers so it is best suited to your specific tendon injury. It is recommended to consult a healthcare professional before starting ultrasound therapy at home, with regular follow-up visits.⁶ The main concern with home ultrasound devices is the risk of causing skin burns, so it is important to move the ultrasound applicator on the skin continuously. The benefit of at-home ultrasound therapy is more frequent treatments.    

Benefits and risks

Positive outcomes and improvements for symptom relief 

Ultrasound therapy has many positive outcomes and improvements that can provide relief from symptoms and help those struggling with tendonitis. Benefits include: 

• Reduced pain
• Reduced swelling and inflammation
• Increased muscular flexibility and function
• Increased blood circulation

Potential side effects and contraindications

The risks of ultrasound therapy are minimal and it should not cause any side effects. Superficial burns are the main side effect of ultrasound therapy, although research shows that the risk is low when properly applied, i.e. with continuous motion.² Ultrasound therapy should not be used on the spine, reproductive organs, eyes or tumours and is not suitable for people with rashes, infections, or active bleeding. Ultrasound therapy should be avoided during pregnancy and by individuals with pacemakers or other cardiac devices.

While ultrasound therapy is generally safe for tendonitis, care should be taken to minimise risk. Ultrasound therapy devices should be monitored and tested regularly for quality assurance purposes.²

Summary

Ultrasound therapy can be an effective treatment option for tendonitis alongside physical therapy. Tendonitis occurs when repetitive movements wear down a tendon, often due to sports or work-related injuries. If left untreated, tendonitis can become a chronic injury and eventually require surgery. 

Ultrasound therapy uses high-frequency sound waves to stimulate and warm the tendons and surrounding tissues, promoting increased blood flow and circulation to the area. There have been successful research studies conducted on the efficacy of ultrasound therapy, though mixed results are due, in part, to the wide array of treatment options. 

The benefits of ultrasound therapy for tendonitis include reduced pain, swelling, and tenderness to the injured area and increased muscular function, flexibility, and blood circulation. Ultrasound therapy is generally considered to be safe when performed correctly by a trained medical professional. There is a small risk of superficial burns to the skin if not performed correctly. Ultrasound therapy is not recommended for use on sensitive parts of the body including the spine, reproductive organs, eyes, or sites of infection.