STUDY: Vibration therapy for a disease triggered by vibration

Shockwave therapy is an ironic treatment for Dupuytren’s contracture: a vibration therapy for a disease that is sometimes actually triggered by vibration.

A scientific review says it works though. So … checkmate, irony!

Today’s featured study is Yazdani et al., a new Iranian review of trials of treating Dupuytren’s contracture with shockwave therapy. Treating what with what? Before we review this review, let’s review what it’s reviewing — which is probably the most interesting part. “Dupu” is weird, and so is shockwave therapy.

Dupuytren’s contracture, showing significant progression of tendon fibrosis, pulling the finger into permanent flexion.

Dupuytren’s and shockwave therapy in a nutshell

Dupuytren’s contracture is an odd disease of slow thickening and lumpiness of the fascia and tendons of the palm, sometimes painfully. The disease is mostly genetic, but can also be triggered by working with vibrating tools for many years.

Which makes shockwave therapy an odd choice of treatment, because — dramatic pause! — shockwave therapy is basically vibration therapy. Yes, you heard that right: vibrations for a condition known to be triggered by vibration! Welcome to my weird world.

Of course, there are many kinds of vibration. Music is all just vibrations, but ranges from inspiring genius to ear-stabbing torture. I’m fine with the way my electric toothbrush vibrates, but the ultrasonic scaler at the dentist is Satan’s work. And clearly a few brief doses of shockwave therapy is not really the same as years of pushing a lawn mower. But I still say it’s odd, ironic, and not entirely risk-free to blast a vibration-triggered disease with more vibrations.

Shockwave therapy is a sibling of ultrasound, but uses pressure waves: low frequency but fast, high energy waves that smack into tissue much harder than sound waves. This makes it even more closely related to massage guns, and with the same vague goal of stimulating tissue. No one really knows exactly why shockwave therapy would work, although there’s no shortage of speculation.

So it’s just a potent vibration, applied to Dupuytren’s because it has a reputation for being good for many orthopedic conditions for unclear reasons — a reputation that is not even deserved! There’s mostly just an absence of shockwave evidence, and what evidence we do have is — as usual — cherry-picked and overrated by the many professionals who sell shockwave therapy, and sincerely don’t want to read the fine print. (Read more.)

So, do shocking waves help people with Dupuytren’s? Some thin science says “yes!”

Yazdani et al. auditioned twenty-six studies, tossed out twenty, and reviewed the remaining six teeny tiny trials — just 145 patients covered by all of those. But studies don’t have to be big to be worthwhile, and these researchers judged five to be “good” quality, and one “fair.”

I think they might have been a bit too generous.

But — good news, everyone! — those six studies of uncertain quality collectively showed “remarkable improvement” in pain and function, as measured by the pain-scale and various disability questionnaires. One study also reported improved grip.

And another reported actual shrinkage of the distinctive bumps and lumps of Dupuytren’s contracture! So maybe shockwave therapy can “melt” contractures somehow? That would be a way bigger deal than merely improving pain and function — that’s changing the course of the disease. If it really does, that’s some crazy physiology, fascinating and important. But I rather doubt it. And so do Yazdani et al, who rated their confidence in that evidence “low.” (Even though it came from a study they rated as “fair”? Seems like a bit of a contradiction there.)

The review concludes (with some slightly stilted English):

“Shockwave therapy can lead to significant pain improvement, functional rehabilitation, and patient satisfaction with no adverse effect in the management of Dupuytren disease. Pain may return over time, but not to that severity [sic] before the intervention.”

For whatever a small review of a small body of evidence is worth. Reviews are worse than laws and sausages: the more we know about how they’re made, the less we like them (hat tip to Mark Crislip).