Ultrasound Treatment for Osteoarthitis

Assessing the Benefits of Ultrasound Therapy for Arthritis

A physical therapist performs a therapeutic ultrasound on a patient's knee.
How does therapeutic ultrasound work for arthritis?. Hero Images/Getty Images

Therapeutic ultrasound is an option in physical therapy to treat pain and loss of joint function due to osteoarthritis. How does it work and what do we know about its effectiveness?

What Is Therapeutic Ultrasound?

Therapeutic ultrasound is a technique which utilizes sound waves (which cause vibration) to decrease pain or improve joint function. These vibrations occur at high frequency—so high that the vibrations are undetectable to the person receiving ultrasound treatment.

The vibrations may be pulsed or continuous. 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.

Typically, therapeutic ultrasound is performed in a physical therapy clinic or in a doctor's office. Although it is a treatment option for osteoarthritis, its effectiveness is still questioned.

Therapeutic ultrasound differs from diagnostic ultrasound in that therapeutic ultrasound is used for treatment (as a therapy) whereas diagnostic ultrasound is used to diagnose disease (or manage pregnancy.) Just as diagnostic ultrasound has been around for quite some time, therapeutic ultrasound has been available since 1950.

How Does Therapeutic Ultrasound Work for Arthritis?

Therapeutic ultrasound may work by either thermal or non-thermal (mechanical) effects.

When using ultrasound for thermal effects, tissues must reach a temperature of 40°C to 45°C (104 F to 113 F) for at least 5 minutes.

Effectiveness of Therapeutic Ultrasound on Knee and Hip Arthritis

Studies evaluating the effectiveness of therapeutic ultrasound on arthritis have been mixed; some studies finding no benefit, and others finding some benefits, especially in osteoarthritis of the knee.

Overall, there has been few studies evaluating the benefits of therapeutic ultrasound, and the studies we have are often small or unreliable. Further research is needed, but let's look at what we know at the current time.

In 2008, a study was published in the Journal of the Canadian Chiropractic Association that reviewed conclusions from experimental, clinical, and animal studies of therapeutic ultrasound for osteoarthritis. Using a PubMed search starting in the year 1985, researchers found 16 studies that met their criteria for inclusion in the review. There were nine studies that concluded therapeutic ultrasound has beneficial effects on pain and function. Five small studies suggested that ultrasound had cartilage healing properties. One experimental study showed increased absorption of hyaluronan using ultrasound phonophoresis. There was just one study that concluded there was no effect on pain or range of motion when ultrasound treatment was combined with exercise. Also, of five review papers, two concluded there were positive effects from therapeutic ultrasound, two did not find any benefit, and one was inconclusive.

In 2010, a Cochrane review of studies utilizing therapeutic ultrasound for knee and hip osteoarthritis was performed.

The review evaluated studies that compared ultrasound to sham or no intervention for pain and function. Five small trials, involving a total of 341 patients with knee osteoarthritis, were included in the Cochrane review. Two of the five evaluated pulsed ultrasound, two evaluated continuous ultrasound, and one evaluated a combination of pulsed and continuous ultrasound. Reviewers concluded that ultrasound may be beneficial for osteoarthritis of the knee. Yet, they were uncertain about how significant the beneficial effects were on pain and function and felt there was a need for better designed studies.

Yet another study published in 2011 in the journal Orthopaedic Surgery, concluded that ultrasound significantly relieved joint symptoms and joint swelling, while improving joint mobility and reducing inflammation in people with osteoarthritis. The study involved 87 people with knee osteoarthritis who received ultrasound treatment for 9 months.

More recently, a 2016 study looking at the effectiveness of low energy pulsed ultrasound on 106 people with osteoarthritis of the knee did find that therapeutic ultrasound was valuable in reducing pain (for about 4 weeks) and improving function and quality of life. It should be noted that this was a very small study on which to base these conclusions, and at the current time more research is needed.

Molecular Effects of Therapeutic Ultrasound on Arthritis

Overall, there are few reliable studies looking at the biological theory behind therapeutic ultrasound, and at the current time it's uncertain how it works (if it does) in treating arthritis. Arthritis is characterized by the breakdown of cartilage, abnormal bone growth in response, as well as changes in soft tissue such as the synovial membrane, ligaments, and muscles which surround the joints.

The thermal effects may reduce spasm in muscles and ligaments, although this is limited, as muscles do not absorb energy well and a large treatment area is required.

In studies looking at people (in vivo studies) it's thought that the main effects of ultrasound therapy on arthritis are mechanical, not thermal. The mechanical effects may work to stimulate cartilage directly.

Based on studies in rats, pulsed ultrasound appears to have regenerative effects on tissues and cartilage. While this is optimistic, we know that studies in other animals are not always a reliable indication of what will occur with humans. There is not much evidence at this time that therapeutic ultrasound has any direct effect on cartilage in humans.

Bottom Line on the Benefits of Therapeutic Ultrasound for Osteoarthritis

Therapeutic ultrasound may work for some people with osteoarthritis of the knee or hip, but more research is needed before these treatments would be considered solid "evidence-based medicine." There are theories about how therapeutic ultrasound may work on a molecular level, but this, as well, is uncertain; there is insufficient biophysical evidence to back the effectiveness of ultrasound on improving cartilage or nearby structures at the molecular level. Yet therapeutic ultrasound is a non-invasive treatment which appears to be very safe, has few adverse effects, and relatively inexpensive.

Osteoarthritis is extremely common, affecting roughly half of people over the age of 65 to some degree, and can play a large role in reducing quality of life. There are a wide range of treatments available ranging from pharmaceutic medications to "natural" treatments such as magnets. While less research has been done on non-invasive and non-medication therapies (ranging from therapeutic ultrasound to acupuncture), it does not mean these are ineffective. In contrast, we need further research to evaluate these "safer" treatments as we are learn that some of the "standard" treatments for arthritis carry considerable risk, such as the risk of gastrointestinal bleeding from non-steroidal anti-inflammatory medications such as Advil (ibuprofen.)

It's important to work with your doctor to explore the many treatment options available for arthritis, especially since a combination of therapies often works better than any single therapy alone. Finally, the possible role of exercise and diet, such as the anti-inflammatory diet for arthritis cannot be understated, and stress management is essential (we've learned that stress exacerbates pain with arthritis.) Whether you are living with arthritis or not, take a moment to look at these 70 ways to reduce stress to begin living a less stressful (and hopefully, less painful) life today.

Sources:

Jia, L., Wang, Y., Chen, J., and W. Chen. Efficacy of Focused Low-Intensity Pulsed Ultrasound Therapy for the Management of Knee Osteoarthritis: A Randomized, Double Blind, Placebo-Controlled Trial. Scientific Reports. 2016. 6:35453.

Rutjes, A., Nuesch, E., Sterchi, R., and P. Juni. Therapeutic Ultrasound for Osteoarthritis of the Knee or Hip. Cochrane Database of Systematic Reviews. 2010. (1):CD003132.

Continue Reading