Does ultrasound work?

The proposed biophysical effects of therapeutic ultrasound have fallen largely out of favour with people that research the modality.  So why is ultrasound still a multi-billion-dollar industry?  It’s an imperfect world I guess, and it takes a long time for a previously well-intentioned therapy/modality/belief to fall out of favor with those that use it.  Therapeutic ultrasound is quite possibly no better than placebo.  There is a shocking (pun intended) lack of evidence for shockwave therapy as well (a more “intense” version of ultrasound).  I don’t enjoy being negative, but there must be critics in healthcare, if positive change is going to occur.

There might be a reader or two thinking, “well, I’ve had ultrasound and it seemed to work”.  I hear this all the time.  The purpose of the research studies (on Ultrasound, or any modality), is to weed out confirmation bias, belief perseverance, and illusory correlation.  So, for example, if a patient had ultrasound on a painful shoulder three times per week over the course of 1 month, and experienced a significant dissipation in pain, they might assume that it was the ultrasound that lead to these results, when it may have simply been the passage of time, or due to any other mix of confounding variables.

Here is Paul Ingraham, talking about this very subject, a little more eloquently (link to his full article: PainScience Ultrasound article)

“It’s not rocket science. Ultrasound is not a difficult therapy to test,10 and if it works reasonably well, then the results should be pretty clear: simply compare results in patients who received real ultrasound to patients who get a fake instead. To a shocking degree, these simple tests have simply not been done adequately. There should be hundreds of them in the archives. Instead there are just a few dozen.

Between 1995 and 2008, the science that has been done was reviewed in only ten papers that seem worthwhile (11,12,13,14,15,16,17,18,19,20,21). Nine were unambiguously negative about US, and some of them strongly so. Their authors had almost nothing good to say about ultrasound. Conclusions like this one from Windt et al are typical:

As yet, there seems to be little evidence to support the use of ultrasound therapy in the treatment of musculoskeletal disorders. The large majority of 13 randomized placebo-controlled trials with adequate methods did not support the existence of clinically important or statistically significant differences in favour of ultrasound therapy.

Windt et al, “Ultrasound therapy for musculoskeletal disorders: a systematic review,” Pain, 1999″