Summary of findings
Low-back pain (LBP) is the most frequent self-reported type of musculoskeletal pain. It is often recurrent and has important socioeconomic consequences. Estimates of the prevalence of LBP vary considerably between studies and reach 33% for point prevalence, 65% for one-year prevalence, and 84% for lifetime prevalence. Chronic non-specific LBP and its resulting disability have become an enormous health and socioeconomic problem (Walker 2000).
The main objectives of treatment for LBP are for the patient to return to their desired level of activity and participation and to prevent chronic complaints and recurrences (Bekkering 2003). The fact that there are many types of treatment for LBP, each of which has multiple subcategories, is testament that no single approach has been able to demonstrate its superiority (Haldeman 2008). Evidence shows that the effectiveness of some interventions is supported (e.g. exercise) (Hayden 2005) while other interventions are not effective for LBP (e.g. traction) (Gay 2001; Wegner 2013). This situation makes it very challenging for clinicians, policy makers, insurers, and patients to make decisions regarding which treatment is the most appropriate for chronic LBP.
The effectiveness of ultrasound for musculoskeletal problems remains controversial. Two systematic reviews on the effects of ultrasound therapy for different musculoskeletal disorders found that there are few studies on this topic and that there is a dearth of evidence regarding its usefulness in the treatment of shoulder disorders, degenerative rheumatic disorders, and myofascial pain (Robertson 2001; van der Windt 1999). The effectiveness of ultrasound for LBP is also still debated (Airaksinen 2006; Ebadi 2011; NICE 2009).
Description of the condition
LBP is defined as pain and discomfort in the lumbosacral region, below the last rib and above the gluteal crease. According to the recommended diagnostic triage, three types of LBP can be defined: 1) non specific LBP; 2) LBP with nerve root symptoms; and 3) LBP resulting from serious pathology (e.g. malignancy, fracture, ankylosing spondylitis). Non-specific LBP, in which there is no recognised patho-anatomical cause, is usually a benign, self-limiting condition. Using the traditional classification system, LBP is also categorised according to its duration as acute (shorter than six weeks), sub-acute (six to 12 weeks) and chronic (longer than 12 weeks) (Krismer 2007; Waddell 2004).
Description of the intervention
Therapeutic ultrasound is frequently used by physiotherapists in the treatment of LBP and is almost certainly the most widely used electro-physical agent in current clinical practice (Blanger 2010). Ultrasound is also commonly used for musculoskeletal disorders by other health professionals such as osteopaths, chiropractors, and sports therapists.
The hypothesis is that therapeutic ultrasound delivers energy to deep tissue sites through ultrasonic waves, to produce increases in tissue temperature or non-thermal physiologic changes (Allen 2006). Unlike ultrasound for medical imaging (which transmits ultrasonic waves and processes a returning echo to generate an image), therapeutic ultrasound is a one-way energy delivery which uses a crystal sound head to transmit acoustic waves at 1 or 3 MHz and at amplitude densities between 0.1 watts/cm² and 3 watts/cm² (Allen 2006; Robertson 2006).
Therapeutic ultrasound can be delivered in two modes, continuous or pulsed. Continuous ultrasound involves the delivery of non-stop ultrasonic waves throughout the treatment period; while in pulsed ultrasound the delivery of is intermittently interrupted (Robertson 2006). Traditionally, continuous ultrasound is used for its thermal effects. Pulsed ultrasound is thought to minimise the thermal effects, however, it is not possible to truly isolate the thermal and non-thermal effects as both effects occur with ultrasound application (Robertson 2006).
How the intervention might work
Ultrasound refers to vibrations that are essentially the same as sound waves but of a higher frequency, beyond the range of human hearing. Therapeutic ultrasound is assumed to have thermal and mechanical effects on the target tissue that results in an increased local metabolism, circulation, extensibility of connective tissue, and tissue regeneration (Robertson 2006).
When acoustic energy is absorbed as it penetrates soft tissues, it causes molecules to vibrate under repeated cycles of compression waves and rarefaction waves. The higher the intensity of the ultrasonic beam and the more continuous the emission of acoustic waves, the more vigorous the molecular vibration or kinetic energy. The more vigorous the micro-friction, the more frictional heat is generated in the tissue (Dyson 1976). Tissue heating is presumed to enhance tissue cell metabolism, which in turn is believed to promote soft-tissue healing. Tissue heating is clearly of value in numerous clinical conditions, through mechanisms of pain relief and improving tissue flexibility, but the evidence does not fully support the use of ultrasound as an efficient thermal intervention (Watson 2008).
Historically, ultrasound has been widely employed for its thermal effects, but it has been argued more recently that the ‘non-thermal’ effects of this energy form are more effective (Watson 2008). The physical mechanisms thought to be involved in producing these non-thermal effects include cavitation and acoustic streaming (micro-massage). Cavitation is triggered by the absorption of acoustic energy and begins when minute gas pockets that infiltrate most biological fluids develop into microscopic bubbles, thus causing cavities in these fluids and the surrounding soft tissues. Under the sustained influence of acoustic radiation, these microscopic bubbles expand and contract (pulsate or oscillate) at the same carrier frequency at which the acoustic waves are produced. Microstreaming is the minute flow of fluid in the vicinity of the pulsating bubbles and is triggered by stable cavitation. These two phenomena are proposed to cause increased cell permeability and affect the course of cell growth, which in turn can improve tissue healing (O'Brien 2007).
Why it is important to do this review
Despite the widespread use of ultrasound in the field of physiotherapy for LBP patients, there is still insufficient evidence of its effectiveness, appropriate intensity and dosage for LBP patients (Airaksinen 2006; Ebadi 2011; NICE 2009). This is the first systematic review to evaluate the effectiveness of therapeutic ultrasound for patients with chronic LBP.
The objective of this review is to determine the effectiveness of therapeutic ultrasound in the management of chronic non-specific low-back pain (LBP). We compared ultrasound (either alone or in combination with another treatment) with placebo, no treatment, or other interventions for chronic LBP. A secondary objective was to determine the most effective dosage and intensity of therapeutic ultrasound for chronic LBP.
Criteria for considering studies for this review
Types of studies
Only randomised controlled trials (RCTs) that evaluated the use of therapeutic ultrasound as a treatment in patients with chronic LBP and that were published as full reports (i.e. not abstracts or conference proceedings) were considered for inclusion in this systematic review. Only studies with a follow-up longer than one day were included.
Types of participants
Studies were included if they recruited adult patients with chronic non-specific LBP. Studies of post-operative patients and patients in whom a specific cause for their LBP had been determined (e.g. vertebral fracture, malignancy) were excluded.
Types of interventions
All RCTs that had compared ultrasound therapy (continuous or pulsed) with other interventions or placebo for chronic LBP were included. Studies were excluded if ultrasound was one part of a treatment package and for which it was not possible to determine the effectiveness of ultrasound alone. For example, we did not include a study that compared aerobic exercise + home exercise to hot pack + ultrasound + TENS (transcutaneous electrical nerve stimulation), but included a study comparing an exercise program with ultrasound to the same exercise program without ultrasound.
Types of outcome measures
Primary outcome measures were: symptoms (e.g. pain), overall improvement or satisfaction with treatment, back-specific functional status (e.g. measured with the Roland Morris Questionnaire, Oswestry Disability Index), well-being (e.g. quality of life measured with the SF-36, SF-12, EuroQol), and disability (e.g. ability to perform activities of daily living, return-to-work status, work absenteeism) (Furlan 2009). The timing of outcome measurements was reported as short term (closest to four weeks), intermediate term (closest to six months), and long term (closest to one year).
Secondary outcome measures included lumbar range of motion, muscle strength and endurance.
Search methods for identification of studies
To identify all relevant RCTs that met the inclusion criteria a search of CENTRAL (The Cochrane Library, October 2013), MEDLINE (1966 to October 2013), EMBASE (1988 to October 2013), PEDro (up to October 2013), and PsycLIT (1974 to October 2013) databases was performed, using the search strategy recommended by the Cochrane Back Review Group (Furlan 2009). A highly sensitive search strategy to retrieve controlled trials (Appendix 1) was used in conjunction with a specific search for low-back pain and therapeutic ultrasound. Studies published in all languages were considered for inclusion.
Searching other resources
To supplement the electronic search strategy, reference lists from relevant publications and reviews were screened and Science Citation Index was used to perform citation tracking of the RCTs identified by the first step. Additionally, we contacted experts in the field of therapeutic ultrasound to identify other relevant articles which may have been missed by the electronic search.
Data collection and analysis
Selection of studies
Two review authors (SE & NH) screened the titles and abstracts of all retrieved studies to identify those meeting the inclusion criteria. The studies were selected independently and the results discussed to make the final selection. A final decision was made for each study after reading the full text of all potentially eligible articles. In cases of disagreement, a third review author (MvT) was consulted.
Data extraction and management
A standardised data extraction form was used to extract data from the included papers. Extracted data included study characteristics (e.g. country, recruitment modality, study funding, risk of bias), patient characteristics (e.g. number of participants, age, sex, severity of LBP), description of the experimental and control interventions, co-interventions, duration of follow-up, outcomes assessed, and results. The same two review authors who conducted the study selection independently extracted the data. All disagreements were discussed and a third review author was consulted if necessary.
Assessment of risk of bias in included studies
Two review authors (SE & NH) independently assessed the risks of bias in each included study using the updated Cochrane Back Review Group criteria which are shown in Appendix 2 and are based on the criteria in the updated Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). In cases of disagreement, a third review author (MvT) was consulted. Attempts were made to obtain additional information from authors of the studies regarding any items that remained unclear. Studies meeting at least six of the 12 criteria and having no serious flaws were considered to have a "low" risk of bias (Furlan 2009).
Measures of treatment effect
Continuous outcomes were analysed by calculating the mean difference (MD) with 95% confidence intervals (CI) when studies used the same outcome measure, or the standardised mean difference (SMD) with 95% CI when studies used different outcome measures for the same construct. If dichotomous outcomes has been reported, we would have calculated the risk ratio (RR) as the effect measure. In cases where more than two interventions were evaluated in the same study, a single "pair-wise" comparison was made. This was necessary to correct for error introduced by "double-counting" of participants in the meta-analyses. For each treatment comparison, an effect size and a 95% CI were calculated and displayed as forest plots. All analyses were conducted in Review Manager v.5.1.
Dealing with missing data
Where any required data were missing, multiple attempts to contact corresponding authors of the studies were made. Where no contact was possible with the authors, these studies were excluded from the meta-analyses.
Assessment of heterogeneity
Clinical heterogeneity of the included RCTs was assessed by considering whether the studies were similar for the setting, participants, interventions and outcomes. Methodological heterogeneity was evaluated by examining the variability in study design and risk of bias. Statistical heterogeneity was checked using the Chi² test with the level of significance at 0.05. Values of I² that are greater than 80% show a very high level of heterogeneity, in which case, pooling of studies was not performed. If values of I² were 40% to 79%, studies were pooled using a random-effects model; in cases of low or no heterogeneity, studies were pooled using a fixed-effect model.
Where possible, the outcome measures from the individual RCTs were combined through meta-analysis provided sufficient homogeneity (i.e. I² < 80%) existed between studies. The clinical relevance of the results was evaluated using five criteria (Appendix 3) and considered in the 'Summary of the findings' table. The criteria include items on the reporting of patients, interventions and treatment settings, as well as assessing likely treatment benefits in relation to potential harms. An improvement of 30% on LBP or function was considered as a clinically important change (Ostelo 2005).
The overall quality of the evidence was evaluated using the GRADE approach (Guyatt 2008). The quality of the evidence for a specific outcome was based on performance against five principal domains: 1) limitations (due to risk of bias), 2) consistency of results, 3) directness (i.e. generalisability), 4) precision (sufficient data with narrow confidence intervals) and 5) other (e.g. publication bias). Single studies were considered to provide "low" or "very low" quality evidence, depending upon whether they were associated with a low or high risk of bias, respectively. The following levels of the quality of the evidence were applied.
- High quality: Further research is very unlikely to change the level of evidence.
- Moderate quality: Further research is likely to have an important impact on confidence in the estimate of effect and may change the estimate.
- Low quality: Further research is very likely to have an important impact on confidence in the estimate of effect and is likely to change it.
- Very low quality: We are very uncertain about the estimate.
Description of studies
Results of the search
The search strategy for the current review identified 868 references from electronic databases and 42 records from additional sources (Figure 1). After removal of duplicates, 910 unique articles were screened for inclusion. After screening the titles and abstracts, full text copies of 58 trials were retrieved. The reference lists of previous reviews were checked but did not result in the identification of any further relevant studies. After reviewing the full text of the 58 selected trials, both review authors (SE, NH) agreed on the inclusion of seven trials and exclusion of 51 trials.
|Figure 1. Study flow diagram.|
Six articles published in English and one Croatian article (which was translated by a native speaker) were included in this systematic review. Outcome measures and intervention details are described below as well as in the Characteristics of included studies table. All studies were performed in secondary care settings, usually in outpatient physiotherapy departments. The seven included studies had mostly small sample sizes, with only one study (Mohseni-Bandpei 2006) having more than 25 participants per treatment arm. One study with three arms compared ultrasound to no treatment and electrical stimulation (Durmus 2010b), one study compared ultrasound plus exercise to phonophoresis plus exercise and exercise alone (Durmus 2013), four studies compared therapeutic ultrasound to placebo or sham ultrasound (i.e. application of ultrasound with the machine turned off) (Ansari 2006, Durmus 2010a, Ebadi 2012, Grubisic 2006), and one study compared ultrasound to spinal manipulation (Mohseni-Bandpei 2006). All studies except for one (Ansari 2006) used stretching or strengthening exercise as an additional intervention to ultrasound therapy while Durmus 2010a also provided hot packs to both groups.
All studies used 1 MHz continuous ultrasound at intensities between 1 W/cm
Further details of some excluded studies are presented in the Characteristics of excluded studies table. The most common reasons for exclusion were that the ultrasound therapy was used as part of a combination treatment and its effect could not be separated from other therapies, or patients had specific causes of low back pain (such as spinal stenosis).
Risk of bias in included studies
The final results of the 'Risk of bias' assessment are shown in Figure 2. Two studies (29%) had a low risk of bias, meeting six or more of the 12 criteria .
|Figure 2. 'Risk of bias' summary: review authors' judgements about each risk of bias item for each included study.|
Only two studies clearly described the randomisation procedure and only one reported a concealed allocation procedure. Most studies did not report sufficient details on either the method of randomisation or allocation, thus they were judged as "unclear" for these items.
Participants were blinded to group allocation in four studies (Ansari 2006; Durmus 2010a; Ebadi 2012; Grubisic 2006) through the use of sham ultrasound (i.e. application of ultrasound with the machine turned off or output set to zero). In the three studies that compared ultrasound with other treatments (Durmus 2010b, Durmus 2013, Mohseni-Bandpei 2006), blinding of patients was not carried out. In no study was the care provider blinded to group allocation. Because the primary outcome measure in all studies was self-reported, the risk of outcome assessor bias was low in the studies in which patients were blinded.
Incomplete outcome data
In five studies (Durmus 2010a, Durmus 2010b, Durmus 2013, Ebadi 2012, Mohseni-Bandpei 2006) dropout rates were explained and acceptable. The rate of dropout in the study by Ansari 2006 was 30% of the (already very small) sample size, which renders a high risk of attrition bias. In three studies (Ansari 2006, Durmus 2010b, Durmus 2013) participants who dropped out were excluded from the analysis. Two studies (Durmus 2010a; Ebadi 2012) reported that an intention-to-treat analysis was performed.
Other potential sources of bias
None of the studies reported on compliance with the intervention. Three studies (Ansari 2006; Durmus 2013; Ebadi 2012) controlled for co-interventions, and all studies assessed their outcomes at similar time intervals for all groups. No study mentioned any conflict of interest in regard to commercial funding.
Effects of interventions
Therapeutic ultrasound versus placebo
Three studies (n = 121) provided post-treatment data on pain intensity (Durmus 2010a; Ebadi 2012; Grubisic 2006). There was low quality evidence (imprecision, inconsistency) that therapeutic ultrasound provides no significant improvement in pain intensity when compared to placebo (mean difference (MD) [95%CI] -7.12 [-17.99 to 3.75]) (Figure 3, Analysis 1.1).
|Figure 3. Forest plot of comparison: 1 Ultrasound vs. sham ultrasound, outcome: 1.1 Pain (VAS) post-treatment.|
Three studies (n = 100) provided post-treatment data on back-specific function (Ansari 2006; Durmus 2010a; Ebadi 2012). There was moderate quality evidence (imprecision) that therapeutic ultrasound improves back-specific function when compared to placebo (standardised mean difference (SMD) [95%CI] -0.45 [-0.84 to -0.05]) (Figure 4, Analysis 1.2).
|Figure 4. Forest plot of comparison: 1 Ultrasound vs. sham ultrasound, outcome: 1.2 Back-specific functional status post-treatment.|
Three studies (n = 89) provided post-treatment data on lumbar flexion range of motion (ROM) (Ansari 2006; Ebadi 2012; Grubisic 2006). There was very low quality evidence (limitations in design, imprecision, inconsistency) that therapeutic ultrasound provides no improvement in flexion ROM when compared to placebo (SMD [95%CI] 0.18 [-0.62 to 0.98]) ( Analysis 1.3).
Two studies (n = 58) provided post-treatment data on lumbar extension ROM (Ansari 2006; Ebadi 2012). There was moderate quality evidence (imprecision) that therapeutic ultrasound provides no improvement in extension ROM when compared to placebo (SMD [95%CI] -0.33 [-0.85 to 0.19]) ( Analysis 1.4).
Therapeutic ultrasound plus exercise versus exercise alone
Both studies (n = 79) provided post-treatment data on pain intensity measured with the Pain Disability Index. There was low quality evidence (imprecision, limitations in design) that therapeutic ultrasound in addition to exercise provides no significant improvement in pain intensity when compared to exercise alone (MD [95%CI] -2.16 [-4.66 to 0.34]) (Figure 5, Analysis 2.1).
|Figure 5. Forest plot of comparison: 2 Ultrasound in addition to exercise vs. exercise alone, outcome: 2.1 Pain (PDI) post-treatment.|
Both studies (n = 79) provided post-treatment data on back-specific functional status measured with the Oswestry Disability Questionnaire. There was low quality evidence (imprecision, limitations in design) that therapeutic ultrasound in addition to exercise provides no significant improvement in functional status when compared to exercise alone (MD [95%CI] -0.41 [-3.14 to 2.32]) (Figure 6, Analysis 2.2).
|Figure 6. Forest plot of comparison: 2 Ultrasound in addition to exercise vs. exercise alone, outcome: 2.2 Back-specific functional status post-treatment.|
Both studies (n = 79) also provided post-treatment data on flexion ROM measured with the Lumbar Schober method. There was low quality evidence (imprecision, limitations in design) that therapeutic ultrasound in addition to exercise provides no significant improvement in flexion ROM when compared to exercise alone (MD [95%CI] 0.02 [-0.52 to 0.56]) ( Analysis 2.3).
Therapeutic ultrasound versus other treatments
Three studies (Durmus 2010b; Durmus 2013; Mohseni-Bandpei 2006) compared therapeutic ultrasound with other treatments for chronic low back pain. There is very low quality evidence that there is no significant post-treatment difference on any outcome measure between electrical stimulation and therapeutic ultrasound (Durmus 2010b). There is very low quality evidence that phonophoresis results in improved SF-36 scores compared to therapeutic ultrasound (Durmus 2013). There is low quality evidence that spinal manipulation results in a significantly greater reduction in pain intensity and functional disability, as well as improved lumbar flexion and extension than therapeutic ultrasound post-treatment and after six months (Mohseni-Bandpei 2006).
All included studies described the parameters (intensity, duration, frequency) for ultrasound application. Most described the patients in sufficient detail and reported on at least one relevant outcome measure (e.g. pain, functional disability). However, very few of the included studies reported intermediate- or long-term outcomes. In addition, no study showed a clinically significant effect size in favour of ultrasound and in light of the potential for harm associated with the application of ultrasound, the benefits could not be clinically justified ( Table 1).
Summary of main results
Seven small randomised controlled trials (362 participants) met the inclusion criteria for this review (Ansari 2006; Durmus 2010a; Durmus 2010b; Durmus 2013, Ebadi 2012; Grubisic 2006; Mohseni-Bandpei 2006). From three trials (n = 100) there was moderate quality evidence that therapeutic ultrasound improves back-specific function (SMD = -0.45) compared with placebo in the short term. From two trials (n = 58) there was moderate quality evidence that ultrasound provides no improvement in extension ROM compared with placebo in the short term.
There was low quality evidence from two trials (n = 79) that therapeutic ultrasound in addition to exercise does not significantly reduce pain intensity or improve back-specific function or flexion ROM when compared with exercise alone. There was also low quality evidence (three studies; n = 121) that therapeutic ultrasound is not better than placebo with regards to short-term pain improvement; and that spinal manipulation significantly reduces pain and functional disability more than ultrasound post-treatment and after six months (one study; n = 112).
For all other comparisons and follow-up time points there was either very low quality evidence or no evidence.
Overall completeness and applicability of evidence
The lack of intermediate- and long-term outcome assessment in most of the studies included in this review restricts our ability to comment on whether any effects of therapeutic ultrasound were maintained. In most of the included studies, therapeutic ultrasound was evaluated in combination with some form of exercise therapy, which limits any conclusions on the effectiveness of ultrasound as a uni-modal treatment. Within the included studies, not all recommended outcome measures for studies on low-back pain (LBP) (such as pain and back-specific function) were measured by all studies (Furlan 2009). The reporting of ultrasound application parameters and dose was inconsistently reported in the included studies, which meant that no conclusions on the most effective dose could be made. No study reported on calibration of the ultrasound device prior to or between treatment sessions.
Quality of the evidence
The small sample sizes in the included studies led to a downgrading of the evidence (i.e. imprecision) for most of the treatment comparisons. As a result, there was mostly low to very low quality evidence to support the use of therapeutic ultrasound. Most studies were affected by poor reporting, which made assessment of the risk of bias difficult. While most studies blinded the patient or outcome assessor, no study was able to appropriately blind the caregiver (therapist). In addition, there was a lack of information from all studies about compliance with therapeutic ultrasound or adverse events.
Potential biases in the review process
All attempts were made to reduce the bias involved with the review process. Where any of the review authors were also authors of one of the included studies, external reviewers were consulted to apply the eligibility criteria, extract the data, and perform the 'Risk of bias' assessment. In the case of missing data, attempts were made to gather the information from authors of the included studies.
Implications for practice
There is a lack of large, high quality studies that have investigated the effect of therapeutic ultrasound for chronic LBP which makes it difficult to reach a definitive conclusion on its effectiveness. Different outcome measures are used by the studies to highlight various aspects faced by patients with chronic LBP. Nevertheless, effect sizes are small and mostly imprecise between therapeutic ultrasound and no treatment or placebo. While there may be a small effect of therapeutic ultrasound on certain outcome measures, it is not clear whether the improvements are clinically meaningful. Although ultrasound is still widely used in most parts of the world in clinical practice, the body of evidence is not strong enough to support ultrasound as an effective treatment for patients with chronic LBP.
Implications for research
Further research is likely to have an important impact on our confidence in the estimate of effect of therapeutic ultrasound for chronic LBP and may change the estimate. In order to identify whether therapeutic ultrasound has any clinically important effect on chronic LBP and investigate the implications of varying dose, intensity, and application type, randomised controlled trials with low risk of bias and adequate sample size are required. Future trials would need to include long-term outcome measurements, record any potential adverse effects, and consider the cost-effectiveness of ultrasound treatment in order to improve the evidence base.
The authors would like to thank Rachel Couban for assistance in developing the electronic search strategy. The authors would also like to thank Steven Kamper and Zoe Michaleff for their assistance in assessing the risk of bias and data extraction for one included study.
Data and analyses
- Top of page
- Summary of findings [Explanations]
- Authors' conclusions
- Data and analyses
- What's new
- Contributions of authors
- Declarations of interest
- Sources of support
- Differences between protocol and review
- Index terms
Appendix 1. MEDLINE and other search strategies
Search Strategies Ultrasound for LBP
1. randomized controlled trial.pt.
2. controlled clinical trial.pt.
5. drug therapy.fs.
10. (animals not (humans and animals)).sh.
11. 9 not 10
13. exp Back Pain/
15. (lumbar adj pain).ti,ab.
19. sciatic neuropathy/
22. exp low back pain/
23. spondylosis.mp. or exp Spondylosis/
24. back pain.mp.
26. 11 and 25
31. 26 and 30
1. Clinical Article/
2. exp Clinical Study/
3. Clinical Trial/
4. Controlled Study/
5. Randomized Controlled Trial/
6. Major Clinical Study/
7. Double Blind Procedure/
8. Multicenter Study/
9. Single Blind Procedure/
10. Phase 3 Clinical Trial/
11. Phase 4 Clinical Trial/
12. crossover procedure/
18. (clinic$ adj25 (study or trial)).mp.
27. ((singl$ or doubl$ or trebl$ or tripl$) adj25 (blind$ or mask$)).mp.
29. (versus or vs).mp.
31. 14 and 30
34. exp ANIMAL/
35. Animal Experiment/
36. 33 or 34 or 35
37. 32 not 36
38. 31 not 36
39. 37 and 38
40. 38 or 39
42. back pain.mp.
43. exp BACKACHE/
44. (lumbar adj pain).mp.
48. exp ISCHIALGIA/
51. exp Low back pain/
57. 40 and 52 and 56
S56 S50 and S55
S55 S51 or S52 or S53 or S54
S52 (MH "Ultrasonics")
S51 (MH "Ultrasonic Therapy")
S50 S48 AND S28
S49 S28 and S48
S48 S35 or S43 or S47
S47 S44 or S45 or S46
S45 (MH "Spondylolisthesis") OR (MH "Spondylolysis")
S44 (MH "Thoracic Vertebrae")
S43 S36 or S37 or S38 or S39 or S40 or S41 or S42
S42 lumbar N2 vertebra
S41 (MH "Lumbar Vertebrae")
S37 (MH "Sciatica")
S36 (MH "Coccyx")
S35 S29 or S30 or S31 or S32 or S33 or S34
S34 lumbar N5 pain
S33 lumbar W1 pain
S31 (MH "Low Back Pain")
S30 (MH "Back Pain+")
S28 S26 NOT S27
S27 (MH "Animals")
S26 S7 or S12 or S19 or S25
S25 S20 or S21 or S22 or S23 or S24
S21 followup stud*
S20 follow-up stud*
S19 S13 or S14 or S15 or S16 or S17 or S18
S18 (MH "Prospective Studies+")
S17 (MH "Evaluation Research+")
S16 (MH "Comparative Studies")
S15 latin square
S14 (MH "Study Design+")
S13 (MH "Random Sample")
S12 S8 or S9 or S10 or S11
S9 (MH "Placebos")
S8 (MH "Placebo Effect")
S7 S1 or S2 or S3 or S4 or S5 or S6
S3 clinical W3 trial
S2 "randomi?ed controlled trial*"
S1 (MH "Clinical Trials+")
#1 MeSH descriptor Back explode all trees
#2 MeSH descriptor Buttocks, this term only
#3 MeSH descriptor Leg, this term only
#4 MeSH descriptor Back Pain explode tree 1
#5 MeSH descriptor Low Back Pain, this term only
#6 (low next back next pain)
#8 MeSH descriptor Sciatic Neuropathy explode all trees
#9 MeSH descriptor Spine explode all trees
#10 MeSH descriptor Spinal Diseases explode all trees
#11 (#1 OR #2 OR #3 OR #4 OR #5 OR #6 OR #7 OR #8 OR #9 OR #10)
#12 MeSH descriptor Ultrasonics explode all trees
#15 (#12 OR #13 OR #14)
#16 (#11 AND #15)
Abstract and title: ultrasound
Body Part: lumbar spine, sacroiliac joint or pelvis
Method: clinical trial
S1 , Publication Type:Clinical Trial
S2 , Publication Type:Controlled Clinical Trial
S3 , Publication Type:Randomized Controlled Trial
S4 Subject:"Clinical Trials" OR Subject:"Clinical Trials as Topic" OR Subject:"Controlled Clinical Trials"
S5 Subject:"Randomized Controlled Trials as Topic" OR Subject:"Prospective Studies" OR Subject:"Comparative Study"
S6 All Fields:random* OR All Fields:placebo* OR All Fields:sham*
S7 All Fields:versus OR All Fields:vs
S8 All Fields:"clinical trial" OR All Fields:"controlled trial"
S9 All Fields:double-blind OR All Fields:"double blind"
S10 All Fields:single-blind OR All Fields:"single blind"
S11 S1 OR S2 OR S3 OR S4 OR S5 OR S6 OR S7 OR S8 OR S9 OR S10
S12 Subject:"Back" OR Subject:"Back Injuries" OR Subject:"Back Pain"
S13 Subject:"Low Back Pain" OR Subject:"Lumbar" OR Subject:"Lumbosacral Region"
S14 Subject:"Sciatica" OR All Fields:sciatica
S16 Subject:"Coccyx" OR Subject:"Sacroiliac Joint" OR Subject:"Sacrum"
S24 Subject:"Intervertebral Disk" OR All Fields:disc OR Subject:"Spine"
S25 S12 OR S13 OR S14 OR S16 OR S24
S26 Subject:"Ultrasonic Therapy" OR Subject:"Ultrasonics" OR All Fields:ultrasound
S 27 S11 AND S25 AND S26
Appendix 2. Criteria for assessing risk of bias for internal validity
Random sequence generation (selection bias)
Selection bias (biased allocation to interventions) due to inadequate generation of a randomised sequence
There is a low risk of selection bias if the investigators describe a random component in the sequence generation process such as: referring to a random number table, using a computer random number generator, coin tossing, shuffling cards or envelopes, throwing dice, drawing of lots, minimisation (minimisation may be implemented without a random element, and this is considered to be equivalent to being random).
There is a high risk of selection bias if the investigators describe a non-random component in the sequence generation process, such as: sequence generated by odd or even date of birth, date (or day) of admission, hospital or clinic record number; or allocation by judgement of the clinician, preference of the participant, results of a laboratory test or a series of tests, or availability of the intervention.
Allocation concealment (selection bias)
Selection bias (biased allocation to interventions) due to inadequate concealment of allocations prior to assignment
There is a low risk of selection bias if the participants and investigators enrolling participants could not foresee assignment because one of the following, or an equivalent method, was used to conceal allocation: central allocation (including telephone, web-based and pharmacy-controlled randomisation); sequentially numbered drug containers of identical appearance; or sequentially numbered, opaque, sealed envelopes.
There is a high risk of bias if participants or investigators enrolling participants could possibly foresee assignments and thus introduce selection bias, such as allocation based on: using an open random allocation schedule (e.g. a list of random numbers); assignment envelopes were used without appropriate safeguards (e.g. if envelopes were unsealed or non-opaque or not sequentially numbered); alternation or rotation; date of birth; case record number; or other explicitly unconcealed procedures.
Blinding of participants
Performance bias due to knowledge of the allocated interventions by participants during the study
There is a low risk of performance bias if blinding of participants was ensured and it was unlikely that the blinding could have been broken; or if there was no blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding.
Blinding of personnel/care providers (performance bias)
Performance bias due to knowledge of the allocated interventions by personnel/care providers during the study
There is a low risk of performance bias if blinding of personnel was ensured and it was unlikely that the blinding could have been broken; or if there was no blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding.
Blinding of outcome assessor (detection bias)
Detection bias due to knowledge of the allocated interventions by outcome assessors
There is low risk of detection bias if the blinding of the outcome assessment was ensured and it was unlikely that the blinding could have been broken; or if there was no blinding or incomplete blinding, but the review authors judge that the outcome is not likely to be influenced by lack of blinding, or:
- for patient-reported outcomes in which the patient was the outcome assessor (e.g. pain, disability): there is a low risk of bias for outcome assessors if there is a low risk of bias for participant blinding (Boutron 2005)
- for outcome criteria that are clinical or therapeutic events that will be determined by the interaction between patients and care providers (e.g. co-interventions, length of hospitalisation, treatment failure), in which the care provider is the outcome assessor: there is a low risk of bias for outcome assessors if there is a low risk of bias for care providers (Boutron 2005)
- for outcome criteria that are assessed from data from medical forms: there is a low risk of bias if the treatment or adverse effects of the treatment could not be noticed in the extracted data (Boutron 2005)
Incomplete outcome data (attrition bias)
Attrition bias due to amount, nature or handling of incomplete outcome data
There is a low risk of attrition bias if there were no missing outcome data; reasons for missing outcome data were unlikely to be related to the true outcome (for survival data, censoring unlikely to be introducing bias); missing outcome data were balanced in numbers, with similar reasons for missing data across groups; for dichotomous outcome data, the proportion of missing outcomes compared with the observed event risk was not enough to have a clinically relevant impact on the intervention effect estimate; for continuous outcome data, the plausible effect size (difference in means or standardised difference in means) among missing outcomes was not enough to have a clinically relevant impact on observed effect size, or missing data were imputed using appropriate methods (if dropouts are very large, imputation using even "acceptable" methods may still suggest a high risk of bias) (van Tulder 2003). The percentage of withdrawals and dropouts should not exceed 20% for short-term follow-up and 30% for long-term follow-up and should not lead to substantial bias (these percentages are commonly used but arbitrary, not supported by literature) (van Tulder 2003).
Selective Reporting (reporting bias)
Reporting bias due to selective outcome reporting
There is low risk of reporting bias if the study protocol is available and all of the study's pre-specified (primary and secondary) outcomes that are of interest in the review have been reported in the pre-specified way, or if the study protocol is not available but it is clear that the published reports include all expected outcomes, including those that were pre-specified (convincing text of this nature may be uncommon).
There is a high risk of reporting bias if not all of the study's pre-specified primary outcomes have been reported; one or more primary outcomes is reported using measurements, analysis methods or subsets of the data (e.g. subscales) that were not pre-specified; one or more reported primary outcomes were not pre-specified (unless clear justification for their reporting is provided, such as an unexpected adverse effect); one or more outcomes of interest in the review are reported incompletely so that they cannot be entered in a meta-analysis; the study report fails to include results for a key outcome that would be expected to have been reported for such a study.
Group similarity at baseline (selection bias)
Bias due to dissimilarity at baseline for the most important prognostic indicators.
There is low risk of bias if groups are similar at baseline for demographic factors, value of main outcome measure(s), and important prognostic factors (examples in the field of back and neck pain are duration and severity of complaints, vocational status, percentage of patients with neurological symptoms) (van Tulder 2003).
Co-interventions (performance bias)
Bias because co-interventions were different across groups
There is low risk of bias if there were no co-interventions or they were similar between the index and control groups (van Tulder 2003).
Compliance (performance bias)
Bias due to inappropriate compliance with interventions across groups
There is low risk of bias if compliance with the interventions was acceptable, based on the reported intensity/dosage, duration, number and frequency for both the index and control intervention(s). For single-session interventions (e.g. surgery), this item is irrelevant (van Tulder 2003).
There is low risk of bias if all randomised patients were reported/analysed in the group to which they were allocated by randomisation.
Timing of outcome assessments (detection bias)
Bias because important outcomes were not measured at the same time across groups
There is low risk of bias if all important outcome assessments for all intervention groups were measured at the same time (van Tulder 2003).
Bias due to problems not covered elsewhere in the table
There is a low risk of bias if the study appears to be free of other sources of bias not addressed elsewhere (e.g. study funding).
Appendix 3. Assessing the clinical relevance
1. Are the patients described in detail so that you can decide whether they are comparable to those that you see in your practice?
2. Are the interventions and treatment settings described well enough so that you can provide the same for your patients?
3. Were all clinically relevant outcomes measured and reported?
4. Is the size of the effect clinically important?
5. Are the likely treatment benefits worth the potential harms?
Last assessed as up-to-date: 1 October 2013.
Contributions of authors
Review authors SE, NH, and MvT designed the protocol. SE and NH screened the studies, extracted the data and performed the analyses. SE drafted the manuscript with help from the other authors. All authors read and approved the final version.
Declarations of interest
Maurits van Tulder is a Co-ordinating Editor of the Cochrane Back Review Group, therefore he was not part of the peer review or publication decision-making process. In trials considered for inclusion, where one of the authors is also an author of this review, that author was not involved in decisions regarding the inclusion, 'Risk of bias' assessment, or conclusions of the trial. The authors declare that they have no other conflicts of interest.
Sources of support
- Institute of Public Health, University of Heidelberg, Germany.
- No sources of support supplied
Differences between protocol and review
Due to the small number of included studies, there were insufficient data to perform any subgroup or sensitivity analyses. In addition, funnel plots were not created.
The trial by Licciardone 2013 was originally excluded from the review due to a lack of sufficient data. The trial authors are being contacted to provide this data for the future updates of this review.
Medical Subject Headings (MeSH)
MeSH check words