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Can knuckle cracking cause arthritis?

Monday, August 21, 2006
Arthritis affects more than three million Australians and contrary to popular belief, more than half the sufferers are under 65.

Are you adding yourself to that number by cracking your knuckles? We're about to find out if knuckle cracking can give you arthritis.

Tina Lymberis could crack for Australia.

"The sensation I get when I crack parts of my body is just sheer relief, because I feel a lot of tension build up during the day or periods of stress and the only way I can relieve it is to crack my knuckles," says Tina.

But Tina's getting a little worried, could she be causing long term damage?

"To me, now I think I've reached the point where I will do it within reason or I try to become a bit more conscious of the fact that I'm doing it and that it could potentially be harming me, especially if I'm going out of my way to crack any part of my body," she says.

The woman who can answer Tina's concerns is rheumatologist Dr Mona Marabani. She's acting President of Arthritis Australia.

"A lot of people think they feel better after they've cracked their neck or cracked their knuckles and indeed, momentarily, I think that's the case. But whether it's stretching muscles or just a habit that somehow releases stress we don't know. But certainly the improvement isn't long-standing."

When you crack your knuckles you increase the space between your joints. This decreases the pressure of the fluid around them — sucking the ligament inwards. A gas bubble forms which causes the first 'pop' noise you hear. You may hear a second pop which is the ligaments snapping back into place. Could this encourage arthritis?

Arthritis is an umbrella term for about 120 conditions. The most common forms are osteo-arthritis caused by wear and tear on the joints and rheumatoid arthritis which occurs when inflammation damages joints.

The things that arthritis of all types have in common is that it can cause pain, swelling and stiffness in joints.

Before we bring Tina in to have her joints examined for arthritis, we first have a test of our own.

We've found six strong men — three who are knuckle-crackers and three who aren't. We're going to compare their grip strength, because if cracking causes arthritis, and arthritis impairs hand function ... the crackers should be weaker.

We've challenged them to a set of grip tests such as crushing cans, bending nails, tearing thick cardboard and picking up weights with their finger tips.

First challenge

Tear a deck of playing cards. It takes quite a grip to tear a deck of cards in half, but the crackers get the winning hand.

Second challenge

Pick up and hold two, two inch handles, each weighing 136 kilos, in each hand. This will surely test a cracker's grip.

Cracker: 45 seconds, that'll take some beating.

Non-cracker: not even close, 29 seconds. It's another win for the crackers.

Third challenge

Now everyone's favourite, nail bending — it's a real knuckle tester. It's another win for the crackers, they lead three nil.

Can the non-crackers redeem themselves?

Fourth challenge

Contrary to expectations, the crackers lead three nil, but the non-crackers can tie it all up in the final test ... the classic phone book tear.

The crackers finally win this last challenge.

This suggests there's not much difference in grip strength between crackers and non-crackers — and therefore it doesn't cause arthritis.

But, it's hardly definitive, so let's find out for sure.

Remember Tina and her crack habit?

We've brought Tina to see Dr Mona Marabani — one of Australia's leading arthritis experts.

"So let's have a look at your fingers and let me know if anything I do hurts you. I'm just going to feel each of the small joints in your fingers … So far what I'm feeling is normal joints, no swelling of the soft tissues, no swelling of the bones, everything feels very, very normal," says Dr Marabani.

Good news for Tina. So is Tina lucky or is there no link between arthritis and cracking your knuckles?

"There is no risk in what you're doing in terms of future function of your joints, so I'd be very happy to say go along and crack your joints if you want to, it's probably harmless," says the good doc.

What about potential problems to the other joints Tina loves to crack, like her neck or back?

"There's no reason to suspect that any other joint would be any different. So I think you'll find it's the same sort of issue involved," Dr Marabani says.

Tina: "That's really great news. I'm so excited that I can crack my knuckles without worrying about whether it's going to cause arthritis or not." So there it is … you can crack away as much as you like and you won't be doing any damage to your joints. But you may lose a few friends — who just can't stand the habit!

  • This old wives' tale seems to have been parental advice to both deter children from making an annoying noise, and from causing potential damage to their fingers. The 'pop' or 'cracking' sound when we crack our knuckles certainly dramatises the action, giving many people the impression that joint disorders, especially arthritis, will most certainly result in years to come.


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