Therapeutic ultrasound for chronic low-back pain

Ultrasound is a treatment that uses vibration to deliver heat and energy to parts of the lower back—including spinal muscles, ligaments, tendons and bones. Its goal is to reduce pain and speed healing. Chronic low back pain is low-back pain that lasts longer than 12 weeks.

Review Question: Is ultrasound a safe and effective treatment for chronic low-back pain?

We looked for randomised controlled trials (a type of study) that compared ultrasound with other treatments. All the people in these studies were adults (age 18 or over) with chronic “non-specific back pain”. Chronic “Non-specific back pain” is back pain with no known cause that lasts more than 12 weeks.

The comparison treatments included exercise, electrical treatments, spinal manipulation and “placebo treatments”. Placebo treatments are also called “dummy treatments”. They are treatments that have no real treatment effect, such as ultrasound with the ultrasound machine turned off.

The patients who received ultrasound in these studies typically had six to 18 sessions of ultrasound therapy.

We wanted to see if ultrasound helped with pain, quality of life, patient satisfaction, and the ability to perform normal activities of daily living, including work.


Chronic low-back pain is a common cause of pain and problems carrying out normal activities for people around the world. Chronic back pain often causes people to seek medical care, change their lifestyles, and even miss work.

Therapeutic ultrasound is a widely used treatment for low-back pain. When a patient has ultrasound therapy, a healthcare provider uses a hand-held device to rub against the skin over the lower back. The device produces vibration that goes through the skin. The goal is to deliver heat and energy to body parts under the skin, to reduce pain and speed recovery. But it is not clear if ultrasound is a safe and effective treatment or not.

Study Characteristics

We looked for studies (randomised controlled trials) published through to October, 2013. We found seven small studies that included a total of 362 adult patients being treated for chronic low-back pain. All patients in these studies had “non-specific back pain”.

Most of the patients had mild to moderate back pain in terms of pain severity and ability to perform daily activities.

All the studies were performed in “secondary care settings”. In other words, the patients all had been assessed by a physician or other healthcare professional before being treated.

The studies in this review compared ultrasound with other treatments.

Most of the studies only provided short-term follow-up for the patients being treated. In other words, they followed the patients for only a few days or a few weeks. Ideally, studies of treatments for chronic back pain should follow patients for many months or years.

None of the studies reported being commercially funded.

Key Results

We did not find any convincing evidence that ultrasound is an effective treatment for low-back pain. There was no high-quality evidence that ultrasound improves pain or quality of life.

We did find some evidence that ultrasound may improve back-related function—the ability of people to use their backs. But those effects were so small they may not make any difference to patients’ lives.

The studies in this review did not provide information on the safety of ultrasound treatment in terms of injuries or other harmful events related to ultrasound treatment.

Therefore, we cannot determine the effects of ultrasound on chronic back pain based on these studies.

Quality of the Evidence

The quality of the evidence on ultrasound leaves much to be desired. In this review, we found “moderate” quality evidence regarding back-related function. The evidence on other outcomes was of “low” or “very low” quality. There is a great need for further research with larger and better studies.

Authors' conclusions: 

No high quality evidence was found to support the use of ultrasound for improving pain or quality of life in patients with non-specific chronic LBP. There is some evidence that therapeutic ultrasound has a small effect on improving low-back function in the short term, but this benefit is unlikely to be clinically important. Evidence from comparisons between other treatments and therapeutic ultrasound for chronic LBP were indeterminate and generally of low quality. Since there are few high quality randomised trials and the available trials are very small, future large trials with valid methodology are likely to have an important impact on our confidence in the estimate of effect and may change the estimate.

Read the full abstract...

Chronic non-specific low-back pain (LBP) has become one of the main causes of disability in the adult population around the world. Therapeutic ultrasound is frequently used by physiotherapists in the treatment of LBP and is one of the most widely used electro-physical agents in clinical practice.


The objective of this review is to determine the effectiveness of therapeutic ultrasound in the management of chronic non-specific LBP.

Search strategy: 

Electronic searches were performed using CENTRAL, MEDLINE, EMBASE, PEDro, and PsycLIT databases in October 2013. Reference lists of eligible studies and relevant systematic reviews were checked and forward citation searching was also performed.

Selection criteria: 

Randomised controlled trials on therapeutic ultrasound for non-specific chronic LBP were included.

Data collection and analysis: 

Two review authors independently assessed the risk of bias of each trial and extracted the data. When sufficient clinical and statistical homogeneity existed, a meta-analysis was performed. The quality of the evidence for each comparison was determined using the GRADE approach.

Main results: 

Seven small randomised controlled trials involving a total of 362 participants with chronic LBP were included. Two of the studies had a low risk of bias, meeting six or more of the 12 criteria used for assessing risk of bias. All studies were carried out in secondary care settings and most applied therapeutic ultrasound in addition to exercise therapy, at various intensities for six to 18 treatment sessions. There was moderate quality evidence that therapeutic ultrasound improves back-specific function (standardised mean difference (SMD) [95%CI] -0.45 [-0.84 to -0.05]) compared with placebo in the short term. There was low quality evidence that therapeutic ultrasound is no better than placebo for short-term pain improvement (mean difference (MD) [95%CI] -7.12 [-17.99 to 3.75]; zero to100-point scale). There was low quality evidence that therapeutic ultrasound plus exercise is no better than exercise alone for short-term pain improvement (MD [95%CI] -2.16 [-4.66 to 0.34]; zero to 50-point scale), or functional disability (MD [95%CI] -0.41 [-3.14 to 2.32]; per cent). The studies comparing therapeutic ultrasound versus placebo or versus exercise alone did not report on overall satisfaction with treatment, or quality of life. There was low quality evidence that spinal manipulation reduces pain and functional disability more than ultrasound over the short to medium term. There is also very low quality evidence that there is no clear benefit on any outcome measure between electrical stimulation and therapeutic ultrasound; and that phonophoresis results in improved SF-36 scores compared to therapeutic ultrasound. None of the included studies reported on adverse events related to the application of therapeutic ultrasound.