Ultrasound therapy (US) is the use of sound waves above the range of human hearing12 to treat injuries like muscle strains or runner’s knee. It is mostly used by physical therapists, and has been one of the Greatest Hits of musculoskeletal medicine since the 1950s.34 There are many flavours of therapeutic ultrasound, using different intensities and frequencies of sound, but all share the basic principle of “stimulating” or even provoking tissue5 with sound waves above the range of human hearing. Vibration therapy, in other words.
Almost everyone seems to assume that ultrasound is proven — good technological medicine — but that just doesn’t seem to be the case.
Unfortunately — although there are some interesting exceptions and tantalizing hopes for some conditions — ultrasound is not a promising therapy for most of the painful problems it is used for. There is a jarring, bizarre lack of quality research for such a popular, mainstream therapy. What little research is available paints a bland picture. Ultrasound therapy isn’t even on good theoretical foundations. At best, it’s more complicated and unpredictable than most therapists believe. At worst, there is no rational basis for US at all.
Although ultrasound is almost certainly useful for some patients, some of the time, it is not a reliable or evidence-based therapy, and enjoys far more credibility than it deserves.
I do not like the principle of using magic machines to treat.
“Nari,” physical therapist, in an internet forum discussion
Flavours of therapeutic ultrasound
The vast majority of patients will encounter therapeutic ultrasound in one of two forms:
- the ordinary sort familiar to almost anyone who’s had any kind of physical therapy
- its more expensive, intense, painful, and high-tech and over-hyped cousin,6 Extracorporeal Shock Wave Therapy (ESWT)
Garden-variety therapeutic US is cheap and available everywhere. The machines are small, even portable: you can buy small handheld ones. Treatment is brief and painless, and applied (indiscriminately?) to almost any common musculoskeletal problem.
ESWT uses much stronger sound waves — shock waves!7 (Radial “shock” wave therapy is a bit different.8) Treatment is painfully intense and painfully pricey.9 Think of it as fancy ultrasound with a no-pain-no-gain twist.
On the one hand, ESWT is just a “more is better” version of standard US, because it is often used with the same imprecise clinical intention to stimulate/provoke tissues. On the other hand, because it was originally developed for smashing gall stones, ESWT is strong enough to actually disrupt tissue, such as calcifications in tendons — which is a nice precise clinical goal and a whole different kettle of fish.
Therapeutic ultrasound: the lack of science
When I started studying for this article way back in the mid-2000s, I was quite surprised by how little there was to study. Back then, every scientific paper about US pointed out there is not enough research on this topic, or at least not enough good research … and not much has changed. A 2015 review of ultrasound for rotator cuff tendinopathy (cited below) found only six trials, all poor quality.
That’s not a lot to go on, and it’s typical. It’s a bit shocking. We’re talking about ultrasound, here: one of the staples of physical therapy! It’s not a fringe treatment. It practically defines the experience of going to a physiotherapist. Everyone has had that cold gel slapped on an injury, and felt that tingling, penetrating … placebo?
Ultrasound is pseudo-quackery
The disconnect between the popularity of US and the more or less total lack of informative research is troubling. A handful of good studies is a joke for a therapy that is worth literally billions of dollars in the marketplace. How can that much therapy be sold without a satisfactory body of evidence that it works? Bizarre! This is the ultimate example of pseudo-quackery: popular treatments that aren’t overt quackery (they are plausible, not obviously at odds with established science) but fall well short of validated, scientific medicine and are sold with excessive confidence and usually considered mainstream.
This does not mean that US never works for anyone. It does mean that it has been prescribed and sold to patients for decades with unjustified confidence. And that is not cool.
The discouraging state of what little ultrasound evidence there is
In most cases I consider ultrasound less than useless — that's 8-10 minutes wasted that could be used doing something that might actually help.
Jason Silvernail, DPT, Board-Certified in Orthopedic Physical Therapy, in an internet forum discussion
Ultrasound is an unusually easy treatment to test scientifically.10 If it works reasonably well, then the results should be pretty clear. Just compare results in patients who received real ultrasound to patients who get a fake instead! And yet there are just a few dozen such experiments in the scientific literature, and most of them are seriously flawed. Conclusions from evidence reviews like this one from van der 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.
van der Windt et al, 1999, Pain
Did not support the “existence of”? Ouch! Ultrasound’s therapeutic effect has an existential crisis.
Several reviews give a nod towards some ray of hope. For instance, van der Windt et al, despite their overwhelmingly negative conclusion, also noted that “findings for lateral epicondylitis [tennis elbow] may warrant further investigation.” But, naturally, that optimism about tennis elbow is contradicted by other studies.11 The science is mostly a discouraging, unimpressive mess — a classic case (yet another one) of a damning failure to impress.
|van der Windt 199912||musculoskeletal disorders||strongly negative review of 13 “adequate” trials did not support “the existence” of therapeutic effects|
|Robertson 200113||pain and injury||“little evidence” of therapeutic benefit in 10 “acceptable” trials out of 35 candidates; 2 positive trials, 8 negative|
|Baker 200114||biological effects||“insufficient biophysical evidence” to justify therapeutic use for pain and injury|
|Buchbinder 200615||tennis elbow||nine studies produced “platinum” level (better than gold!) evidence of “little or no benefit” (for ESWT)|
|Ho 200716||tennis elbow||conflicting, “unconvincing” evidence of efficacy from a few trials (of ESWT again)|
|Ho 200717||rotator cuff tendinopathy||limited evidence “supports … ESWT for chronic calcific rotator cuff tendinitis,” but no non non-calcific|
|Rutjes 201018||osteoarthritis of knee||a positive update to a previously negative review, which is strange because it’s based on just 5 small, poor quality trials with trivial “positive” results|
|Shanks 201019||lower limb conditions||inconclusive review of 10 of 15 candidates: “no high quality evidence available”|
|van den Bekerom 201120||ankle sprains||inconclusive but discouraging review of “five small placebo-controlled trials”; the “potential treatment effects of ultrasound appear to be generally small”|
|Page 201321||carpal tunnel syndrome||inconclusive but slightly encouraging review of “only poor quality evidence from very limited data” from 11 trials|
|Ebadi 201422||chronic low back pain||inconclusive and underwhelming review of 7 small trials, none of them good quality|
|Desmeules 201523||rotator cuff tendinopathy||negative review “does not provide any benefit … based on low to moderate level evidence” from 11 weak trials|
The bottom line on standard therapeutic ultrasound
Standard therapeutic ultrasound probably does little or nothing for most people. A sliver of hope remains that some specific conditions will respond to ultrasound with just the right settings.
Ultrasound reborn as shockwave therapy
ESWT is high tech. The main implication of this for most patients is that it ain’t cheap.
Extracorporeal Shock Wave Therapy (ESWT) is a technology that uses strong sound waves to “stimulate healing” in tissues — the same vague rationale for essentially all gadget-powered treatments. It can be painfully intense. Think of it as fancy ultrasound with a no-pain-no-gain twist.
Therapeutic ultrasound … has fallen out of favor as research has shown a lack of efficacy and a lack of scientific basis for proposed biophysical effects.
Baker et al, 2001, Physical Therapy
Except it hasn’t fallen out of favour! It’s still widely used. The only professionals it’s fallen out of favour with, I imagine, are a small minority of scientists and unusually alert clinicians.
Not only that, but ultrasound has found new life in the marketplace as shockwave therapy — faster, stronger waves, with a bigger price tag! Consider this marketing language from a Canadian company, Shockwave Institute, specializing in ESWT:
Provided you are a candidate for this type of treatment, clinical studies suggest there is a 80–85% chance this technology will improve your condition.
from the Shockwave Alberta FAQ, as of Nov 30, 2009
Shockwave Alberta certainly doesn’t think ultrasound has fallen out of favour! Here we have an entire company devoted to delivery of therapeutic US, and selling it with the implication that it is not only proven to be effective, but exactly how effective — to within 5%!
Based on the available evidence, do you think it’s actually possible or meaningful to declare that ESWT is exactly “80–85% effective”? Where are the scientific review papers confirming this marvellous triumph of US over whatever ails you? Where is the data to support such a specific promise of therapeutic success? You sure couldn’t find them in 2009.
And how about now? Update on ESWT science
Things seem to have changed for the better, though “80-85% effective” would still be a hard claim to defend.
Bizarrely, ESWT is being used to treat conditions as unexpected as erectile dysfunction, stroke, and venous leg ulcers. There’s even some preliminary evidence for such uses… though not all.
But there are now multiple positive reviews of ESWT for its more common uses, like stubborn cases of plantar fasciitis, a painful irritation of the arch of the foot. A good 2016 example is Lou et al, who concluded that “ESWT seems to be particularly effective in relieving pain associated with recalcitrant plantar fasciitis.”24 Plantar fasciitis is by far the most widely ESWT-treated condition for some reason: other conditions may be a completely different matter, but certainly the evidence for plantar fasciitis is surprisingly good, almost amazingly so (it’s a stark contrast with the vast majority of treatments for musculoskeletal conditions).
A 2009 test of shockwave therapy for hip pain (greater trochanteric pain syndrome) was clearly positive on its face.25
In a similar 2010 test for proximal hamstring tendinopathy, shockwave therapy seemed to handily “win.”26
But a few positive trials doesn’t mean much these days — musculoskeletal medicine is badly polluted with underpowered studies with untrustworthy “promising” results that are mostly good for the CV’s of the researchers who produce them. Cynincism is justified. There’s never been any replication of those hip and hamstring results.
And, despite all that, the evidence is predictably mixed.
Shockwave therapy for adhesive capsulitis (frozen shoulder), for instance, is being sold to patients in the total absence of adequate evidence. There is scarcely any evidence, just a tiny handful of weak studies — including that one that seems most promising.27 For full analysis, see my frozen shoulder article.
And not all reviews have happy endings. A notable general review in the British Medical Journal of Sports Medicine in 2018, of ESWT for “common lower limb conditions,”28 found only a “low level of evidence” that it “may” be effective for some conditions, which is getting pretty wishy-washy. They rejected thirteen studies for a high risk of bias and noted that “a relatively small number of research groups account for the majority of research.” And finally:
There are no occasions where multiple high-quality studies exist for a single pathology, hence for any individual pathology there are low and very low levels of evidence.
In other words, this cannot yet be evidence-based medicine. There’s just not enough (good) evidence. As usual.
Shockwave therapy equipment is generally bigger & more badass.
Patient cynicism about therapeutic ultrasound
There is nothing a cold slimy prickling ultrasound wand can do that a pair of warm hands can’t do way better.
Diane Jacobs, Canadian physiotherapist and writer
If only I had a buck for every time a patient or reader has told me that they are skeptical about “that ultrasound thing they always do to you at physiotherapy”!
Patients often express irritation with a common physical therapy business model: working with several patients at once, rotating between rooms or beds, often leaving patients with passive therapies (like a moist hot pack from a hydrocollator — nice enough, but worth a steep fee?) Many patients often go a step further and complain specifically about ultrasound and TENS, skeptical that these treatments really do anything.29 To the patient, they seem therapeutically unremarkable and also obvious ways for a physiotherapist to get paid while not doing much. This perception really pushes people’s “I don’t want to be a sucker” button.
And so few patients are singing the virtues of standard US. It not only fails to generate testimonials, but actually generates many annoyed antimonials.
Patients do not (yet) feel the same cynicism about shockwave ultrasound. As a more expensive and painful medicine, ESWT is a hope-generating machine. Having spent their hard-earned dollars and endured the discomfort of treatment, patients are more subject to expectation effects (placebo) — and much less willing to entertain the possibility that it was all a waste. At this stage in their quest to feel better, more people will report ambiguous results if they were positive (“Yeah, I think it did some good!”), and even negative reports will often be toned down (“I didn’t seem to get that much out of it, but I guess it works really well for some people.”) This could go on for years.
Few if any patients are out there singing the virtues of standard ultrasound. It not only fails to generate testimonials, but generates many bitter antimonials.
How ultrasound supposedly works
The big idea is — this will blow your mind! — that cells and tissues respond “well” to being shaken (not stirred). In theory, ultrasound works by vibrating tissues back to health, which sounds like something you’d hear on an infomercial, or the Dr. Oz Show. What, exactly, does vibration do to tissues? Does anyone actually understand it?
In 2001, Physical Therapy published a review of the biological effects of ultrasound. More than ten years ago, the authors — Baker, Robertson, and Duck — explained that it had already been at least two decades since it was first pointed out that “physical therapists tended to overlook the tenuous nature of the scientific basis for the use of therapeutic ultrasound.”30 They also point out — it’s the point of their whole paper — that the situation had not improved in twenty years (before 2001):
The frequently described biophysical effects of ultrasound either do not occur in vivo under therapeutic conditions or have not been proven to have a clinical effect under these conditions. This review reveals that there is currently insufficient biophysical evidence to provide a scientific foundation for the clinical use of therapeutic ultrasound …
There is lots of interesting ultrasound biology to consider, and scientists may eventually nail down effects that might be the basis for new evidence-based therapies. For instance, a decade later, Tsai et al declared that “There is strong supporting evidence from animal studies about the positive effects of ultrasound on tendon healing”31 — but animal studies are notoriously misleading, and they certainly can’t justify the use of ultrasound (especially when US has already been tested on tendinopathy with underwhelming results).
Another great example: the persistent hope that rattling cells with sonic vibrations might speed the healing of bone fractures, particularly low intensity pulsed ultrasound (LIPUS). Such an effect, if proven, would certainly be a delightful bit of weird good news about biology. Unfortunately, it is probably dis-proven. In 2017, the British Medical Journal published an excellent review with a very negative conclusion for fresh fractures.32 However, the authors have to concede that “the applicability to other types of fracture or osteotomy is open to debate … ” because it’s impossible to know for sure that there are no black swans anywhere — one could be right around the corner!
Meanwhile, there is still just no basis for thinking that ultrasound has a basis. The entire empire of ultrasound rests on the single, oversimplified idea that “stimulation is good” and the hope that we might someday figure out exactly why. Ultrasound is literally just tissue vibration therapy.
The gate control mechanism: a particularly bogus rationale for ultrasound (especially ESWT)
Physical therapists often cite "counterstimulation and the gate control mechanism as a justification for US and ESWT (and some other popular treatments, especially TENS). This is nonsense, and a great example of why patients should be cautious, especially with the expense of ESWT. It sounds much smarter than it is.
The “gate control” mechanism is an important idea in pain science, proposed in 1965 by Dr. Ronald Melzack and Dr. Patrick Wall,33 and still accepted today as an explanation for a familiar phenomenon: the way we rub injured body parts for a little pain relief. The idea is that pain signals pass through a “gate” in the spinal column, which can be blocked by other sensations, which are (weirdly) given priority by the nervous system.
So the idea with US is that the stimulation of the sound waves closes the gate to pain. This may well occur, because counterstimulation is a real phenomenon — but it’s also nothing to write home about. It’s just a mechanism for transient, minor pain relief. It can be achieved just as easily by rubbing the area yourself! It certainly doesn’t “fix” anything, which is what ultrasound is supposed to be doing. So bringing it up is just a bit of bafflegab, a scientific-sounding rationalization for an expensive therapy. There is no reason to think that any kind of ultrasound closes the gate better or longer than any other stimulus.
The reasons for doing ultrasound are not at all clear, and adding this one is just a way to pad the list — especially handy when you’re trying to sell expensive ESWT, which might also exploit the term counter-irritation — but is actually almost meaningless. It’s disturbingly marketing-savvy, but not at all medically savvy.
A study of ultrasound therapy shows a clear effect on trigger point sensitivity
File this one under “intriguing”: Canadian researchers treated trigger points (muscle knots) in 50 patients with either ultrasound or a sham, and the amount of pressure on the trigger point required to induce pain was measured before and after. Trigger points treated with ultrasound were more tolerant of pressure than those that were not treated, at 1, 3 and 5 minutes after treatment.34 The improvement was no longer significant just 10 and 15 minutes later, however — so the effect in this case was brief. The authors concluded:
… low-dose ultrasound evokes short-term segmental antinociceptive effects on trigger points which may have applications in the management of musculoskeletal pain.
They are not necessarily proposing that ultrasound is a useful treatment for myofascial pain syndrome, but producing evidence of an interesting effect that may prove to be clinically significant in time — an important distinction.
Although it may be surprising in contrast to the generally unimpressive evidence of the effectiveness about therapeutic ultrasound, it nevertheless reinforces that ultrasound does indeed do some interesting things to tissues: it’s just not clear exactly what. An important caveat is that there is significant scientific debate about what “trigger points” really are.35 Some would say it’s hard to study the effect of ultrasound on a phenomenon that may or may not even exist!
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About Paul Ingraham
I am a science writer in Vancouver, Canada. I was a Registered Massage Therapist for a decade and the assistant editor of ScienceBasedMedicine.org for several years. I’ve had many injuries as a runner and ultimate player, and I’ve been a chronic pain patient myself since 2015. Full bio. See you on Facebook or Twitter, or subscribe:
- Zapped! Does TENS work for pain? — The peculiar popularity of being gently zapped with electrical stimulation therapy. TENS is a near sibling to ultrasound: two nearly identical treatment ideas, differing only in the form of stimulation delivered to tissues.
- Tissue Provocation Therapies — Can healing be forced? The laws of tissue adaptation & therapies like Prolotherapy & Graston Technique.
- Cold Laser Therapy Reviewed — A critical analysis of treating pain and injury with frickin’ laser beams.
- Heat for Pain and Rehab — A detailed guide to using heat as therapy for acute and chronic pain and recovery from injury. The discussion of infrared radiation particularly relevant.
- The Chiropractic Controversies — An introduction to chiropractic controversies like aggressive billing, treating kids, and neck manipulation risks.
- Pseudo-Quackery in the Treatment of Pain — The large, dangerous grey zone between evidence-based care and overt quackery in musculoskeletal and pain medicine. Ultrasound is one of the best examples of something in that zone.
- Repetitive Strain Injuries Tutorial — Five surprising and important facts about repetitive strain injuries like carpal tunnel syndrome, tendinitis, or iliotibial band syndrome.
What’s new in this article?
Five updates have been logged for this article since publication (2009). All PainScience.com updates are logged to show a long term commitment to quality, accuracy, and currency. more
Like good footnotes, update logging sets PainScience.com apart from most other health websites and blogs. It’s fine print, but important fine print, in the same spirit of transparency as the editing history available for Wikipedia pages.
I log any change to articles that might be of interest to a keen reader. Complete update logging started in 2016. Prior to that, I only logged major updates for the most popular and controversial articles.
See the What’s New? page for updates to all recent site updates.
2018 — Some science updates for shockwave therapy.
2018 — A couple minor science updates on shockwave therapy (one good news, one bad).
2017 — Science update, cited Schandelmaier et al, an excellent (and completely negative) British Journal of Medicine review of LIPUS for acute fracture/osteotomy healing.
2017 — Added a brief acknowledgement of the surprisingly positive evidence for shockwave therapy for plantar fasciitis, plus a bunch of miscellaneous editing.
2016 — Big science update — Added a table of summarized recent reviews, including six new citations from the last decade (basically all still about scanty, crappy evidence). Several related editorial changes.
2009 — Publication.
- Healthy young adults can hear sounds up to about 20 kilohertz (20,000 hertz). Ultrasound machines produce sound waves from about that frequency and up.
- Below the range of human hearing is “infrasound,” which doesn’t come up much. Some animals, like elephants, use infrasound for communication. Not therapy, as far as we know, but I wouldn’t put it past them! Elephants are clever. Other infrasound communicators: hippos, alligators, whales. Cat purring drops down almost to infrasound range.
- Wong RA, Schumann B, Townsend R, Phelps CA. A survey of therapeutic ultrasound use by physical therapists who are orthopaedic certified specialists. Phys Ther. 2007 Aug;87(8):986–94. PubMed #17553923 ❐ PainSci #55380 ❐
Ultrasound is widely used. This 2007 survey of the usage of ultrasound, the first such American survey for almost 20 years (see Robinson 1988), “examined the opinions of physical therapists with advanced competency in orthopedics about the use and perceived clinical importance of ultrasound.” They found that “ultrasound continues to be a popular adjunctive modality in orthopedic physical therapy. These findings may help researchers prioritize needs for future research on the clinical effectiveness of US.”
- Armijo-Olivo S, Fuentes J, Muir I, Gross DP. Usage Patterns and Beliefs about Therapeutic Ultrasound by Canadian Physical Therapists: An Exploratory Population-Based Cross-Sectional Survey. Physiother Can. 2013;65(3):289–99. PubMed #24403700 ❐ PainSci #53385 ❐
This 2013 Canadian survey of the usage of ultrasound found that “despite the questionable effectiveness of therapeutic US, physical therapists still commonly use this treatment modality, largely because of a belief that US is clinically useful. However, US usage has decreased over the past 15 years.”
- This is also the core principle of numerous other treatment modalities, particularly the gadgets and widgets — your muscle vibrators and lasers and so on — they all stimulate in one way or another, generally with unknown biological and clinical relevance. It would be going a little too far to say that they are all equally dubious (without citations), but after a few years of studying this stuff they do start to seem awfully similar and under-impressive.
- If the Wikipedia page for a treatment sports the warning “appears to be written like an advertisement,” that’s a bright red flag about its validity. Same with the “needs additional citations” warning. As of early 2015, the ESWT page has both.
- Specifically, a strong (fast) sonic pulse for a short length of time (approximately 10 milliseconds). Shockwave therapies use waves travelling faster than the speed of sound (in flesh), about 1500 meters per second.
- There are several different types of extracorporeal shockwave therapy. One of them, radial shockwave therapy, is often called “shockwave” therapy, but probably shouldn’t be, because it uses much lower velocity waves. Radial ultrasound is a couple orders of magnitude slower than other shockwave ultrasound — about 100 meters per second, instead of 1500 — and would be more properly described as a pressure wave therapy. It’s probably not quite fair to lump them all in together when assessing shockwave therapy … but I’m going to do it anyway for now (in my ultrasound article). Until such time as there’s compelling evidence that one flavour has impressively different and better effects than another, it’s all just variations on a theme: stimulating tissues with different sorts of sound waves. Does that seem reasonable?
- ESWT requires much more expensive and sophisticated machinery, and it was extravagantly expensive for a long time. It’s come down a lot, but even now it will run you at least $200 per visit, with a typical prescription of three to six treatments. This is not cheap therapy! I last checked prices in early 2014.
- In particular, even though there are many “flavours,” it’s easy to standardize it for apples-to-apples comparisons, and it’s really easy to fake treatment for a good controlled and blinded test. It’s basically effortless to create a perfect “sham” version of ultrasound, so that the study subjects can’t tell if they are getting the real thing. Many other popular interventions in manual therapy are difficult or even impossible to standardize and/or fake — so it makes more sense that there’s long-term uncertainty about their effectiveness. Ultrasound has much less excuse in this regard.
- Staples MP, Forbes A, Ptasznik R, Gordon J, Buchbinder R. A randomized controlled trial of extracorporeal shock wave therapy for lateral epicondylitis (tennis elbow). J Rheumatol. 2008 Oct;35(10):2038–46. PubMed #18792997 ❐
- van der Windt DA, van der Heijden GJ, van den Berg SG, et al. Ultrasound therapy for musculoskeletal disorders: a systematic review. Pain. 1999 Jun;81(3):257–71. PubMed #10431713 ❐
- Robertson VJ, Baker KG. A review of therapeutic ultrasound: effectiveness studies. Phys Ther. 2001 Jul;81(7):1339–50. PubMed #11444997 ❐ PainSci #55377 ❐
- Baker KG, Robertson VJ, Duck FA. A review of therapeutic ultrasound: biophysical effects. Phys Ther. 2001 Jul;81(7):1351–8. PubMed #11444998 ❐ PainSci #55382 ❐
- Buchbinder R, Green SE, Youd JM, et al. Systematic review of the efficacy and safety of shock wave therapy for lateral elbow pain. J Rheumatol. 2006 Jul;33(7):1351–63. PubMed #16821270 ❐
- Ho C. Extracorporeal shock wave treatment for chronic lateral epicondylitis (tennis elbow). Issues In Emerging Health Technologies. 2007 Jan;(96 (part 2)):1–4. PubMed #17302021 ❐
- Ho C. Extracorporeal shock wave treatment for chronic rotator cuff tendonitis (shoulder pain). Issues In Emerging Health Technologies. 2007 Jan;(96 (part 3)):1–4. PubMed #17302022 ❐
- Rutjes AW, Nüesch E, Sterchi R, Jüni P. Therapeutic ultrasound for osteoarthritis of the knee or hip. Cochrane Database Syst Rev. 2010 Jan;(1):CD003132. PubMed #20091539 ❐
- Shanks P, Curran M, Fletcher P, Thompson R. The effectiveness of therapeutic ultrasound for musculoskeletal conditions of the lower limb: A literature review. Foot (Edinb). 2010 Dec;20(4):133–9. PubMed #20961748 ❐
- van den Bekerom MP, van der Windt DA, Ter Riet G, van der Heijden GJ, Bouter LM. Therapeutic ultrasound for acute ankle sprains. Cochrane Database Syst Rev. 2011 Jun;(6):CD001250. PubMed #21678332 ❐
- Page MJ, O’Connor D, Pitt V, Massy-Westropp N. Therapeutic ultrasound for carpal tunnel syndrome. Cochrane Database Syst Rev. 2013 Mar;(3):CD009601. PubMed #23543580 ❐
- Ebadi S, Henschke N, Nakhostin Ansari N, Fallah E, van Tulder MW. Therapeutic ultrasound for chronic low-back pain. Cochrane Database Syst Rev. 2014 Mar;(3):CD009169. PubMed #24627326 ❐
- Desmeules F, Boudreault J, Roy JS, et al. The efficacy of therapeutic ultrasound for rotator cuff tendinopathy: A systematic review and meta-analysis. Phys Ther Sport. 2015 Aug;16(3):276–84. PubMed #25824429 ❐
- Lou J, Wang S, Liu S, Xing G. Effectiveness of Extracorporeal Shock Wave Therapy Without Local Anesthesia in Patients With Recalcitrant Plantar Fasciitis: A Meta-Analysis of Randomized Controlled Trials. Am J Phys Med Rehabil. 2016 Dec. PubMed #27977431 ❐
- Furia JP, Rompe JD, Maffulli N. Low-energy extracorporeal shock wave therapy as a treatment for greater trochanteric pain syndrome. Am J Sports Med. 2009 Sep;37(9):1806–13. PubMed #19439756 ❐
33 patients were given low-energy shockwave therapy for greater trochanteric pain syndrome, while 33 others were treated with other forms of conservative therapy. Those who got shockwave therapy were the lucky ones: the results were clear and positive, both statistically and clinically significant, and sustained as long as a year later. The study is underpowered and cannot be taken too seriously, but it’s certainly positive on its face. Conclusion: “Shock wave therapy can be an effective treatment for greater trochanteric pain syndrome.”
- Cacchio A, Rompe JD, Furia JP, et al. Shockwave Therapy for the Treatment of Chronic Proximal Hamstring Tendinopathy in Professional Athletes. Am J Sports Med. 2010 Sep. PubMed #20855554 ❐
- Hussein AZ, Donatelli RA. The efficacy of radial extracorporeal shockwave therapy in shoulder adhesive capsulitis: a prospective, randomised, double-blind, placebo-controlled, clinical study. European Journal of Physiotherapy. 2016 Mar;18(1):63–76.
This test of shockwave therapy for frozen shoulder hits all the highlights of well-designed experiment. The researchers gave real shockwave therapy to one group of 52 patients weekly for a month, and sham shockwave therapy to the other group, and measured pain and function. The real shockwave group did “significantly” better, with the researchers notably claiming both statistical and clinical significance of the results … but not reporting the actual effect sizes in the abstract, which is always suspicious (if they are impressive, they get featured).
Despite the good design, a major concern here is that sham treatment. Shockwave therapy is high energy, and uncomfortable at best, painful at worst. In the sham group, the shockwaves were simply “blocked.” It seems like many or most patients would certainly know that they weren’t getting the real shockwave therapy … which would spoil the data for sure.
The results are very promising, but it’s a mystery why shockwave therapy would work, the effect they observed was probably not very large, and there’s probably one huge flaw that would be a deal-breaker.
- Korakakis V, Whiteley R, Tzavara A, Malliaropoulos N. The effectiveness of extracorporeal shockwave therapy in common lower limb conditions: a systematic review including quantification of patient-rated pain reduction. Br J Sports Med. 2018 Mar;52(6):387–407. PubMed #28954794 ❐
- TENS may be more evidence-based than ultrasound, particularly for some specific medical situations, but its widespread, indiscriminate use is definitely dubious. Like ultrasound, it is clearly sold to patients for more purposes than the evidence can possibly support. For more information, see Zapped! Does TENS work for pain?
- Baker 2001, op. cit.
- Tsai WC, Tang ST, Liang FC. Effect of therapeutic ultrasound on tendons. Am J Phys Med Rehabil. 2011 Dec;90(12):1068–73. PubMed #21552108 ❐
- Schandelmaier S, Kaushal A, Lytvyn L, et al. Low intensity pulsed ultrasound for bone healing: systematic review of randomized controlled trials. BMJ. 2017 Feb;356:j656. PubMed #28348110 ❐ PainSci #52780 ❐ From the abstract: “trials at low risk of bias failed to show a benefit with LIPUS, while trials at high risk of bias suggested a benefit” and “LIPUS does not improve outcomes important to patients and probably has no effect on radiographic bone healing.”
- Melzack R, Wall PD. Pain mechanisms: a new theory. Science. 1965 Nov;150(3699):971–9. PubMed #5320816 ❐
This is Melzack and Wall’s seminal paper arguing that (emphasis mine) “pain perception and response is triggered after the cutaneous sensory input has been modulated by both sensory feedback mechanisms and the influences of the central nervous system. We propose that the abstraction of information at the first synapse may mark only the beginning of a continuing selection and filtering of the input.” Among other things, this is the paper that described the mechanism of gate control and ultimately gave rise to the highly influential concept of the neuromatrix (Melzack).
- Srbely JZ, Dickey JP, Lowerison M, et al. Stimulation of myofascial trigger points with ultrasound induces segmental antinociceptive effects: A randomized controlled study. Pain. 2008 Oct 15;139(2):260–6. PubMed #18508198 ❐
- The dominant theory is that a trigger point is basically an isolated spasm affecting just a small patch of muscle tissue. Unfortunately, it’s still just a theory, and trigger point science is a bit half-baked and somewhat controversial, and it’s not even clear that it’s a “muscle” problem. The pain is certainly real, but it isn’t necessarily coming from the muscle at all. See Trigger Point Doubts.