Our 2 experts discuss the history, types, and mechanisms of extracorporeal shockwave therapy in veterinary medicine, highlighting its evolution from lithotripsy in the 1970s to treating musculoskeletal injuries and osteoarthritis since the 1990s
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Adam Christman, DVM, MBA: All right, so let’s talk about shockwave therapy. We’re gonna back up a little bit and talk about the history and basics of extracorporeal shockwave therapy. So Dr. Alvarez, I’m curious to know how long has shockwave therapy been used in veterinary medicine and how did its application evolve over time?
Leilani Alvarez, DVM, DACVSMR, CVA, CCRT: Yeah, shockwave therapy, extracorporeal shockwave therapy has been around for quite some time. In the 1970s, how extracorporeal shockwave therapy first came into the medical world was for lithotripsy. So it was to break up urinary, salivary, and renal calculi. And the reason for that is it generates these very high pressure, high velocity sound waves that then would break up those stones. And then since then that has been further developed into treating musculoskeletal injury. So in the maybe early 1990s, and when we start to see the application of shockwave therapy for treatment of soft tissue injuries, things like tendinopathies, also non-healing bone wounds that you have, for example, a fracture that’s not healing, you have a non-union shockwave can be excellent for that. And even things like osteoarthritis. So it really, it was from the 1990s and early 2000s that it really started to get more of an application in the medical field outside of lithotripsy. And really took off, I would say, in the 2000s in the veterinary field.
Adam Christman, DVM, MBA: Wow, excellent. So how does it work and what’s its mechanism of action?
Leilani Alvarez, DVM, DACVSMR, CVA, CCRT: Before I can answer that, I just wanna take a brief moment to explain because I think people think of shockwave as shockwave is shockwave.
Adam Christman, DVM, MBA: That’s so true.
Leilani Alvarez, DVM, DACVSMR, CVA, CCRT: Yeah, and so I’m gonna try to break it down into really simple terms 'cause I’m a simple-minded person. So there’s focused shockwave and unfocused shockwave. And focused shockwave is electrohydraulic shockwave. That’s what pulse fed is. We also have electromagnetic shockwave and piezoelectric shockwave. Those all fall under the category of focused. Then we have the unfocused shockwave and that would be radial shockwave. We’re also called pneumatic or ballistic shockwave. And I think the better term for that is probably pressure waves because they don’t have the nearest high of energy as the focused shockwave. But there is evidence for radial shockwave, not just on the human side, but also in veterinary medicine. So those are the major two categories. And then within the focused, they’re very different between the electro-hydraulic, electromagnetic, and piezoelectric. How they work is different between those different types of machines. Let’s talk about electro-hydraulic. It has, without question, the highest level of evidence in veterinary medicine. I actually counted nine publications, prospective studies in dogs, demonstrating efficacy of this machine in particular. And then just, it’s actually a friend of mine, just this year, one publication came out on piezoelectric. So we do have one study now on piezoelectric. And electro-hydraulic, I’m just gonna, it’s okay if I–
Adam Christman, DVM, MBA: Yes, absolutely.
Leilani Alvarez, DVM, DACVSMR, CVA, CCRT: Touch our demonstration. This is called a trod. This is what delivers the therapy. And you’ll see that there’s a cord attached to this. This is then attached to electricity. And so basically a spark goes off in here. And this part here, which is soft, has a fluid medium in it. And so when the spark plug goes off in here, it actually sets off little bubbles that then get dispersed as sound waves that come across from here into the tissue. And when that happens, it’s a very, so it’s high pressure, high velocity, but relatively low frequency, which is really interesting when we talk about side effects and things like that. And so we get this pressure wave that comes up very rapidly, but then it actually goes negative. And that sharp negative pressure wave creates a cavitation. So if you think about, like if you had, you know, maybe gel, like you’re making jello or something like that, and you disperse like a high, you know, sound waves into there, it creates bubbles. And that rapid decrease in pressure causes a cavitation. So the bubble bursts basically. And when that happens in the tissue, what's really cool about that is you get massive increase in cellular permeability. So lots of blood flow comes into the area, and it's a big trigger for release of anti-inflammatory cytokines. So that's all the good stuff that helps improve healing. And then the other thing that happens,because this does create a sound and there is sensation at the tissue level, you also get a pretty massive endorphin release. So those are the body's natural painkillers. So that's how it works.
Adam Christman, DVM, MBA: Wow, really neat. Great explanation by the way too.