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Author Topic: What causes joints to crack?  (Read 2918 times)

Offline Seany

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What causes joints to crack?
« on: 05/01/2009 23:03:41 »
The joints clicking.. Usually knuckles and knees..
Why is this? I have heard that it is because it releases air trapped between the bones, creating this crack.. But is it bad for you? Or leads to athritis?
Thank you!
« Last Edit: 05/01/2009 23:25:53 by chris »


 

Offline Chemistry4me

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Joints clicking --- knuckles, knees!
« Reply #1 on: 05/01/2009 23:26:51 »
I don't think there has been any solid evidence which points to clicking joints and arthritis.
 

Offline Madidus_Scientia

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What causes joints to crack?
« Reply #2 on: 06/01/2009 07:12:21 »
I believe this thread will be of interest to you

http://www.thenakedscientists.com/forum/index.php?topic=15262.0
 

Offline Seany

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What causes joints to crack?
« Reply #3 on: 06/01/2009 09:39:03 »
From Paul..

Quote
Some scientists wanted to learn more about knuckle cracking, so they actually stuck a sensitive microphone onto a finger. They found that there wasn't just one single sound when you cracked a finger joint - there were actually two separate sounds. The joint space is the space between the bones. There is a liquid in this space, and there are ligaments on each side, holding the bones together. As you pull on the joint, you first drop the pressure in the joint space - and the ligaments get sucked in. Once this pressure gets low enough, a bubble pops into existence - making a popping sound, which is the first of the two sounds.

Now this bubble has a certain size - on average, about 15% of the now-bigger joint space. Because the joint space suddenly has a bubble in it, the liquid, just as suddenly, pushes on the ligaments - snapping them back to their original position. This snapping back of the ligaments is the second sound.


The energy set loose inside the joint is only about 7% of what you need to damage the cartilage. But if you crack your knuckles often enough, you can end up with swollen ligaments.

Another study looked at 300 people who had been cracking knuckle joints for 35 years. They had slightly swollen joints (which is no big deal). But the real surprise was that their hands were weaker - their grip strength was one quarter as strong as it should been!

Tank yoo Paul!
 

Offline RD

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What causes joints to crack?
« Reply #4 on: 12/01/2009 08:36:12 »
I think the misconception that cracking joints causes arthritis is because cracking joints (crepitus) is a symptom of arthritis,
 (i.e. a consequence being mistaken for a cause).

Quote
Crepitus is a medical term to describe the grating, crackling or popping sounds and sensations experienced under the skin and joints.

The sound can be created when two rough surfaces in the human body come into contact - for example, in osteoarthritis when the cartilage around joints has eroded away and the joint ends grind against one another, or when the fracture surfaces of two broken bones rub together.
http://en.wikipedia.org/wiki/Crepitus
 

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What causes joints to crack?
« Reply #4 on: 12/01/2009 08:36:12 »

 

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