Abstract: We included 12 studies, involving 622 participants with 648 fractures. Eight studies were randomised placebo-controlled trials, two were randomised controlled trials without placebo controls, one was a quasi-randomised placebo-controlled trial and one was a quasi-randomised controlled trial without placebo control. Eleven trials tested LIPUS and one trial tested ECSW. Four trials included participants with conservatively treated upper limb complete fractures and six trials included participants with lower limb complete fractures; these were surgically fixed in four trials. The remaining two trials reported results for conservatively treated tibial stress fractures. 'Risk of bias' assessment of the included studies was hampered by the poor reporting of methods, frequently resulting in the risk of bias of individual domains being judged as ‘unclear’. Both quasi-randomised studies were at high risk of bias, including selection and attrition bias. Three studies were at low risk of selection bias relating to allocation concealment the majority of studies were at low risk of performance bias as they employed a form of intervention blinding. Only limited data were available from three of only four studies reporting on functional outcome. One study of complete fractures found little evidence of a difference between the two groups in the time to return to work (mean difference (MD) 1.95 days favouring control, 95% confidence interval (CI) -2.18 to 6.08; 101 participants). Pooled data from two studies found LIPUS did not significantly affect the time to return to training or duty in soldiers or midshipmen with stress fractures (MD -8.55 days, 95% CI -22.71 to 5.61; 93 participants). We adopted a conservative strategy for data analysis that was more likely to underestimate than to overestimate a benefit of the intervention. After pooling results from eight studies (446 fractures), the data showed no statistically significant reduction in time to union of complete fractures treated with LIPUS (standardised mean difference (SMD) -0.47, 95% CI -1.14 to 0.20). This result could include a clinically important benefit or harm, and should be seen in the context of the highly significant statistical heterogeneity (I² = 90%). This heterogeneity was not explained by the a priori subgroup analyses (upper limb versus lower limb fracture, smoking status). An additional subgroup analysis comparing conservatively and operatively treated fractures raised the possibility that LIPUS may be effective in reducing healing time in conservatively managed fractures, but the test for subgroup differences did not confirm a significant difference between the subgroups. Pooled results from five of the eight trials (333 fractures) reporting proportion of delayed union or non-union showed no significant difference between LIPUS and control (10/168 versus 13/165; RR 0.75; 95% CI 0.24 to 2.28). Adverse effects directly associated with LIPUS and associated devices were found to be few and minor, and compliance with treatment was generally good. One study reporting on pain scores found no difference between groups at eight weeks (101 participants). One quasi-randomised study found no significant difference in non-union at 12 months between internal fixation supplemented with ECSW and internal fixation alone (3/27 versus 6/30; RR 0.56, 95% CI 0.15 to 2.01). There was a clinically small but statistically significant difference in the visual analogue scores for pain in favour of ECSW at three month follow-up (MD -0.80, 95% CI -1.23 to -0.37). The only reported complication was infection, with no significant difference between the two groups. While a potential benefit of ultrasound for the treatment of acute fractures in adults cannot be ruled out, the currently available evidence from a set of clinically heterogeneous trials is insufficient to support the routine use of this intervention in clinical practice. Future trials should record functional outcomes and follow-up all trial participants.

Plain-language summary: This is an update of a review previously published in February 2012. We did a new literature search up till 2 June 2014 but did not find any new studies. There are 12 studies, involving 622 participants with 648 fractures, included in this review. In all the studies we included, participants were assigned randomly to one of two groups, one group receiving treatment by ultrasound and the other group receiving no treatment or sham treatment. Most participants had a recent complete fracture of a single bone. The participants of two trials had 110 incomplete or stress fractures that resulted from heavy exercise. Four trials tested the effects of ultrasound on healing of 203 upper limb fractures and the other trials, on 130 lower limb fractures. The most commonly investigated bone was the tibia (shin bone). Eleven trials tested low-intensity pulsed ultrasound and one trial with 59 fractures tested shockwave therapy. Most trials compared a working ultrasound device with a sham device and thus protected against placebo effects. The placebo effect is a phenomenon whereby patients experience a treatment effect that is not objectively attributable to the treatment itself. However, studies varied substantially in terms of quality and risk of having biased results. In many cases the quality of reporting was poor, which made it difficult to determine which biases might have affected each study. The risk of bias across many domains therefore had to be judged as 'unclear'. The results of many trials were probably biased because of missing data from several trial participants. Additionally, the trials were very different from each other; for example, they varied in the bone that was broken and whether or not the fractures were also treated surgically. Based on analyses that adjusted for these missing data, the available evidence did not confirm that ultrasound improved the time taken for bone healing or prevented the problem of the bone failing to heal at all (eight trials with 333 fractures). The results from one low quality trial (with 59 fractures) testing shockwave therapy were inconclusive. Few complications were reported in any of the studies and these were not related to the ultrasound or shockwave therapy. While a potential benefit of ultrasound for the treatment of acute fractures in adults cannot be ruled out, the currently available evidence from 12 quite different trials is insufficient to support the routine use of ultrasound in clinical practice. Future studies should measure return to full function and normal activity and should try to ensure all participants are followed up.