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Does Ultrasound or Shockwave Therapy Work?

They seem like mainstream physical therapies, but warming and vibrating tissues with sound/pressure waves has never been supported by good evidence

Paul Ingraham • 25m read
Photo of the left side of a man’s upper back, shoulder, and neck, with a bright blue ultrasound wand being applied to the back of his shoulder.

The pressure wave therapies are huge in physical therapy: both ultrasound therapy (US) and extracorporeal shockwave therapy (ESWT) are used to treat pain and injuries like plantar fasciitis, muscle strains, or runner’s knee. Therapeutic ultrasound has been one of the Greatest Hits of musculoskeletal medicine since the 1950s,12 and shockwave therapy has been steadily replacing it in the 21st Century.

Although ultrasound and shockwave therapy are different, all their variants are used in the same ways for the same conditions, and they are all vibration delivery systems, intended to “stimulate” tissue — which, optimistically, might induce regenerative and anti-inflammatory effects in injured bone, cartilage, and tendon. They belong to a whole family of vibration therapies, which also includes massage guns, jacuzzis, and vibrating exercise platforms. The differences between these things are meaningful, but they are all very similar in spirit.

Most people and professionals assume that all of this is good technology, proven medicine — but that just doesn’t seem to be the case. Although there are some interesting exceptions and tantalizing hopes for some conditions, neither ultrasound or shockwave therapy are promising therapies for most of the painful problems they're used for. There is a jarring, bizarre lack of quality research for such mainstream treatment modalities, and the results are not encouraging. At best, it’s complicated and unreliable. At worst, there is just no rational basis for hitting tissues with pressure waves at all, and it’s all just modern snake oil. Interestingly, shockwave therapy is routinely marketed along with much more blatant kinds of quackery.

Although ultrasound and shockwave therapy are almost certainly useful for some patients, some of the time, they are not evidence-based therapies, and enjoy far more credibility than they deserve.

I do not like the principle of using magic machines to treat.

“Nari,” physical therapist, in an internet forum discussion

Ultrasound versus shockwave

Shockwave therapy is often considered a new kind of ultrasound, because they are such similar ideas, used for all the same conditions and similar reasons. But shockwave therapy isn’t “ultra” sound — it’s infra!

Ultrasound uses high-frequency sound waves, above the range of human hearing (> 20,000 Hz) — which vibrates tissue so quickly that it warms up, rather like a gentle microwave. For most people, most of the time, the point of ordinary therapeutic ultrasound is about the same as putting on a magic heating pad with a more penetrating warmth. It’s cheap, harmless, and ubiquitous. You can buy your own small ultrasound machine at the drugstore!

Shockwave therapy is much more like a powerful vibrating massage “gun.” It’s pressure waves are slow and high-energy, smacking the tissue hard, at frequencies in the infrasound range, well below the range of human hearing (< 20 Hz) — which produces much more potent “stimulation,” strong enough to shatter calcifications, and cause micro-injuries that might “kickstart” healing. This is much more expensive than ultrasound, often painful, and there is no DIY shockwave therapy.

Stylized drawing representing ultrasound: a loudspeaker symbol with a red cross on it.

The lack of science about ultrasound and shockwave therapy

When I started studying for this article waaaay 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 was not enough research on this topic, or at least not enough good research.

Incredibly, it hasn't changed. We're still starving for decent evidence, as of a 2024 update to this article.

For instance, a 2015 paper about ultrasound for rotator cuff tendinopathy found only six trials, all poor quality. A big 2020 review of ultrasound for back pain found just 10 trials, and was scathingly critical of their quality: all bad! “The certainty of the evidence for all outcomes was very low.” And so on, with no real improvement since. (These and many other citations coming up below.)

That’s not a lot to go on, and it’s saldy typical for the field of pain treatment and injury rehab. But the poverty of evidence for this topic is a bit shocking. We’re talking about ultrasound, here: one of the staples of physical therapy. Hardly 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 and shockwave therapy are 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, something that has been done to countless pro athletes over the decades. 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 obvious quackery, but still fall well short of validated, evidence-based medicine, and are sold with excessive confidence and usually considered mainstream rather than alternative

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.

Therapeutic ultrasound

Ultrasound uses high-frequency sounds waves, and is familiar to almost anyone who’s had any kind of physical therapy in the last fifty years… and certainly anyone who had it before 2010. Although still widely available in clinics, and on drugstore shelves, ultrasound is slowly dying out, increasingly replaced by shockwave therapy. Some ultrasound basics:

The dubious rationale for ultrasound

In 2001, Physical Therapy published a review of the biological effects of ultrasound. More than ten years earlier, 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.”3 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”4 — 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.5 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!

But the negative conclusion was echoed in another review in 2023.6 The report that “few studies” even reported on patient outcomes. “It is probable that LIPUS makes little or no difference to delayed union or non‐union.” It’s also noteworthy that they only found a single test of shockwave ultrasound, and none at all of high-intensity ultrasound.

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.

The state of the evidence for ultrasound

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.7 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.8 The science is mostly a discouraging, unimpressive mess — a classic case (yet another one) of a damning failure to impress.

An overview of ultrasound reviews: generally underwhelming, with lots of “garbage in, garbage out”!
van der Windt 19999 musculoskeletal disorders strongly negative review of 13 “adequate” trials did not support “the existence” of therapeutic effects
Robertson 200110 pain and injury “little evidence” of therapeutic benefit in 10 “acceptable” trials out of 35 candidates; 2 positive trials, 8 negative
Baker 200111 biological effects “insufficient biophysical evidence” to justify therapeutic use for pain and injury
Buchbinder 200612 tennis elbow nine studies produced “platinum” level (better than gold!) evidence of “little or no benefit” (for ESWT)
Ho 200713 tennis elbow conflicting, “unconvincing” evidence of efficacy from a few trials (of ESWT again)
Ho 200714 rotator cuff tendinopathy limited evidence “supports … ESWT for chronic calcific rotator cuff tendinitis,” but no non non-calcific
Rutjes 201015 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 201016 lower limb conditions inconclusive review of 10 of 15 candidates: “no high quality evidence available”
van den Bekerom 201117 ankle sprains inconclusive but discouraging review of “five small placebo-controlled trials”; the “potential treatment effects of ultrasound appear to be generally small”
Page 201318 carpal tunnel syndrome inconclusive but slightly encouraging review of “only poor quality evidence from very limited data” from 11 trials
Desmeules 201519 rotator cuff tendinopathy negative review “does not provide any benefit … based on low to moderate level evidence” from 11 weak trials
Ebadi 202020 chronic low back pain inconclusive and underwhelming review of 10 little trials, none of them good quality

The bottom line on standard therapeutic ultrasound

Standard therapeutic ultrasound probably does little or nothing for most people and conditions. A sliver of hope remains that some specific conditions will respond to ultrasound with just the right settings.

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.

Shockwave therapy: ultrasound reborn!

Photo in a physiotherapy clinic of a woman delivering extracorporeal shock wave therapy to another woman lying facedown on a table. The ESWT machine is sleek and modern-looking.

Super-duper ultrasound

ESWT is high tech. The main differences for the patient? It ain’t cheap & it’s much more intense.

Extracorporeal Shock Wave Therapy (ESWT), often shortened to just "shockwave therapy, is a more intense, high-tech, expensive,21 over-hyped, "more is better" cousin of therapeutic ultrasound.

Shockwave therapy generates much lower frequency, faster pressure waves than ultrasound. Those waves slap tissues with much higher energy, and at a downright leisurely rhythm — mostly under 10 Hz. Five shockwaves per second (5 Hz) is quite a bit slower than tap dancing, which can get up to about 18 Hz! But that is way below the range of human hearing, which starts around 20 Hz.

So shockwave therapy is infrasound rather than ultrasound.22

Despite these differences, the aim of shockwave therapy is extremely similar: to "stimulate" tissue, the same vague rationale for nearly all gadget-powered treatments. But there are a two significant differences:

Causing microtrauma can be painfully intense. So you can think of shockwave therapy as fancy ultrasound with a no-pain-no-gain twist. Damaging tissue might seem like the wrong idea for something that's supposed to be treating injuries, but there's a specific hypothesis that this will stimulate healing processes that had, for whatever reason, not already been working. This is thought of as a "kickstart" for healing, and it’s the rationale for all of the provocation therapies. This is why shockwave therapy is sometimes called a "regenerative" therapy, which is really a reach.

Breaking up calcifications is a more specific goal, and there's no question that it can be done. Whether it is therapeutically valuable or not is another question, since calcifications probably often aren't actually the cause of a problem, or even the source of ongoing symptoms.

Some bonus shockwave facts…

Hype about the shockwave therapy: profitably misrepresenting the strength of the evidence

Enthusiasm about shockwave therapy has raced ahead of the evidence. 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 (and still a good representative example today)

Shockwave Alberta certainly doesn’t think ultrasound has fallen out of favour! Here we have an entire company devoted to delivery of therapeutic ultrasound, 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. Many years later, it’s still not much clearer.

Shockwave evidence

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 some 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.”25 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.26

In a similar 2010 test for proximal hamstring tendinopathy, shockwave therapy seemed to handily “win.”27

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 without adequate evidence. There is scarcely any evidence, just a tiny handful of weak studies — including that one that seems most promising.28 For full analysis, see my frozen shoulder article.

Another good example of a bad result is Heide et al., in which shockwave therapy for plantar fasciitis couldn’t beat a sham in a good quality new test — following the classic pattern of “better studies undermine weaker early ones.” It almost always goes like this. It’s not a good sign.29

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,”30 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.

More recently, in 2023, Ko et al. concluded that “ the overall confidence in non-surgical treatments from all included trials was very low. No recommendation of the best treatment option can be made.” And the least-lame option they identified was not shockwave but eccentric training.31

Shockwave therapy absolutely cannot be considered evidence-based medicine, despite years of hype to that effect. There’s just not enough (good) evidence — as usual — and what we have is just not that encouraging.

An overview of shockwave therapy reviews: generally underwhelming, with lots of “garbage in, garbage out”! Just like ultrasound! [Actively updating this table in Nov 2024, stay tuned for more soon]
Searle 202332 fracture healing negative review reports absence-of-evidence for acute fractures and shockwave therapy, and that ultrasound makes “little or no difference to delayed union or non‐union”
Yazdani 202433 Dupuytren’s contracture an unambiguously positive conclusion … that I frankly do not trust34

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.35 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.

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,36 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.37 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.38 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

Headshot of Paul Ingraham, short hair, neat beard, suit jacket.

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:

Related Reading

What’s new in this article?

Eight 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 When’s the last time you read a blog post and found a list of many changes made to that page since publication? Like good footnotes, this sets PainScience.com apart from other health websites and blogs. Although footnotes are more useful, the update logs are important. They are “fine print,” but more meaningful than most of the comments that most Internet pages waste pixels on.

I log any change to articles that might be of interest to a keen reader. Complete update logging of all noteworthy improvements to all articles 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.

Oct 31, 2024 — Minor but widespread improvements, and some science updates. Shockwave therapy is becoming a more prominent part of the article as it replaces low-intensity ultrasound in the marketplace.

August — Science update for ESWT for plantar fasciitis.

2022 — Added a sidebar: “Self-serve shockwave therapy? Buyer beware”

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.

Notes

  1. 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 Bibliography 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.”

  2. 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 Bibliography 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.”

  3. Baker 2001, op. cit.
  4. 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 ❐
  5. 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 Bibliography 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.”
  6. Searle HKC, Lewis SR, Coyle C, Welch M, Griffin XL. Ultrasound and shockwave therapy for acute fractures in adults. Cochrane Database Syst Rev. 2023 Mar;3(3):CD008579. PubMed 36866917 ❐ PainSci Bibliography 49769 ❐
  7. 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.
  8. 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 ❐
  9. 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 ❐
  10. Robertson VJ, Baker KG. A review of therapeutic ultrasound: effectiveness studies. Phys Ther. 2001 Jul;81(7):1339–50. PubMed 11444997 ❐ PainSci Bibliography 55377 ❐
  11. Baker KG, Robertson VJ, Duck FA. A review of therapeutic ultrasound: biophysical effects. Phys Ther. 2001 Jul;81(7):1351–8. PubMed 11444998 ❐ PainSci Bibliography 55382 ❐
  12. 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 ❐
  13. 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 ❐
  14. 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 ❐
  15. 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 ❐
  16. 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 ❐
  17. 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 ❐
  18. 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 ❐
  19. 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 ❐
  20. Ebadi S, Henschke N, Forogh B, et al. Therapeutic ultrasound for chronic low back pain. Cochrane Database Syst Rev. 2020 Jul;7(7):CD009169. PubMed 32623724 ❐ PainSci Bibliography 49771 ❐
  21. This 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 $100 per visit, often much more, with a typical prescription of three to six treatments. I last checked prices in 2024.
  22. 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.
  23. Shockwave therapy was adapted from a revolutionary method of smashing gall stones and kidney stones, one of the greater victories of modern medicine, back in the 1980s. That technology was known as "extracorporeal" to emphasize the fact that you didn't have to cut into someone, or insert a probe up the urethra — which, eek, had been routine! In a physical therapy context, the fact that there's no cutting extracorporeal is less meaningful.
  24. There are actually several different types of extracorporeal shockwave therapy. 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. It’s might not even be fair to lump them all in together when assessing shockwave therapy … but I’m going to do it anyway for now. Until such time as there’s compelling evidence that one flavour has impressively different and better effects than another, it’s all just trivial variations on a consistent theme.
  25. 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 ❐
  26. 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.”

  27. 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 ❐
  28. 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.

  29. Heide M, Røe C, Mørk M, et al. Is radial extracorporeal shock wave therapy (rESWT), sham-rESWT or a standardised exercise programme in combination with advice plus customised foot orthoses more effective than advice plus customised foot orthoses alone in the treatment of plantar fasciopathy? A double-blind, randomised, sham-controlled trial. Br J Sports Med. 2024 Jul;58(16):910–918. PubMed 38904119 ❐ PainSci Bibliography 49858 ❐

    This trial was designed to test the efficacy of radial extracorporeal shock wave therapy (rESWT) for plantar fasciitis, by comparing it to a sham, an exercise program, and just advice and orthoses). They recruited 200 patients and split them up into four groups, and checked on at the start and then after 3, 6, and 12 months. The shockwave group got three treatments.

    There were “no statistically significant between-group differences,” so it was a wash: not only no measurable difference between real and fake shockwave therapy, but exercise, advice, and orthoses also all failed to be helpful. The authors concluded:

    “In patients with plantar fasciopathy, there was no additional benefit of rESWT, sham-rESWT or a standardised exercise programme over advice plus customised foot orthoses in alleviating heel pain.”

  30. 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 ❐
  31. Ko VMC, Cao M, Qiu J, et al. Comparative short-term effectiveness of non-surgical treatments for insertional Achilles tendinopathy: a systematic review and network meta-analysis. BMC Musculoskelet Disord. 2023 Feb;24(1):102. PubMed 36750789 ❐ PainSci Bibliography 49666 ❐
  32. Searle HKC, Lewis SR, Coyle C, Welch M, Griffin XL. Ultrasound and shockwave therapy for acute fractures in adults. Cochrane Database Syst Rev. 2023 Mar;3(3):CD008579. PubMed 36866917 ❐ PainSci Bibliography 49769 ❐
  33. Yazdani A, Nasri P, Baradaran Mahdavi S. The Effects of Shock Wave Therapy on the Symptoms and Function of Individuals With Dupuytren Disease: A Systematic Review. Arch Phys Med Rehabil. 2024 Oct;105(10):1985–1992. PubMed 38866227 ❐
  34. It may be correct, of course, but this is a small review of dubious quality, looking at a handful of tiny studies that almost certainly had a high risk of bias. Garbage in, garbage out. Similar reviews of shockwave therapy for conditions in this pathological family (e.g. Peyronie’s) are much the same, and some are more negative. For more detailed analysis, see the shockwave section in my Dupuytren’s contracture guide.
  35. 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?
  36. 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).

  37. 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 ❐
  38. 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.

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