Therapeutic ultrasound for chronic low-back pain

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