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Dublin: 10 °C Friday 24 October, 2014

Debunked: Does knuckle-cracking cause arthritis?

A loud cracking sound coming from inside your hand can’t be a good thing, right?

Do you like that loud cracking sound?
Do you like that loud cracking sound?

IN A NEW series, TheJournal.ie takes a look at an urban myth, old wives’ tale, or something that your mammy told you years ago to see if there’s any truth in it.

For some it is a ghastly annoyance similar to nails on a chalkboard, for others it’s a source of immense satisfaction, but most people would consider cracking your knuckles as something to be avoided.

This is down to a long-running myth that the cracking sound is caused by bones clicking against each other. The thinking is that this weakens them, eventually leaving the hand susceptible to developing osteoarthritis. This actually isn’t what’s happening at all.

It’s all bubbles

The process is actually based on liquid and air.

When a joint is moved in a certain way to crack it, air pressure in the joint cavity decreases and forms an environment similar to a suction cup. This allows microscopic bubbles to form in the synovial fluid, which is essentially the body’s WD40 which lubricates the joint. These little bubbles combine together into one big bubble.

Eventually, at some point during the movement, more synovial fluid rushes in to the cavity and causes that bubble to — you guessed it — pop.



But is this rather bubbly process causing any damage?

Speaking to TheJournal.ie, Gráinne O’Leary, Head of Education and Support Services with Arthritis Ireland, has a rather unequivocal answer:

“No, it is a definitely a myth.”

And it’s not just Gráinne who say so. Several studies, for example here and here have shown that there is no conclusive evidence to form a link between cracking knuckles and arthritis.

Less grip

However, that doesn’t mean you habitual knuckle crackers out there are being let off scot-free.

“If you are a chronic knuckle cracker,” Gráinne warned, “some studies have shown you may lose some grip in your hands.

“But whether or not you crack your knuckles, it doesn’t mean you definitely won’t get arthritis. There are many different kinds which can be triggered in many different ways, but the three golden rules to avoid it would be to eat healthy, exercise, and don’t smoke.”

Nobel Prize… almost

Before we put this topic to bed, let’s spare a moment for Dr Donald Unger.

He dedicated sixty years of his life investigating a link between cracking joints and arthritis — using his own body as the test subject, cracking only the knuckles on his left hand.

He found that neither his left nor his right hand developed arthritis. The study earned him an Ig Nobel Prize, an award for “achievements that first make people laugh, and then make them think” which bears no relation to its more illustrious namesake.

Is there a myth you’d like debunked? Email nicky@thejournal.ie

Hat-tip to Daithí Naughton who suggested this week’s topic.

Read: New findings may provide relief for osteoarthritis sufferers >

Debunked: Do you really eat a dozen spiders in your sleep every year? >

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