I’ve often asked myself, why do my joints crack and so I decided to find the 
answer. If you also have cracking or popping joints you may be interested in this short post on the subject. For me, it’s my knees. The sound is really loud and if I have to bend my knees, the whole room knows about it!
Why do my joints crack? – Common explanation
It would appear that the best explanation for this unsettling noise when you bend down or move a joint… is gas! Gas from within the cavity formed in your joint. When you bend your knees or crack your knuckles, the space between the bones changes. This creates a differing pressure which can draw your synovial fluid into the gap created by that change. This was researched in the 1970s and it was published that the cracking was due to popping of bubbles in the fluid in your joints.
New research – forming a vacuum (2018)
Now new research using a MRI video has found that it’s not popping bubbles. it’s actually the formation of a gas-filled cavity. When the joint moves, it causes a vacuum. That causation makes the noise. The study author Greg Kawchuk from the University of Alberta said:
“It’s a little bit like forming a vacuum… As the joint surfaces suddenly separate, there is no more fluid available to fill the increasing joint volume, so a cavity is created and that event is what’s associated with the sound.”
Old research – forming a vacuum (1940s)
This theory was suggested way back in the 1940s, without the help of a MRI video. But it was dismissed in favour of the bubble popping theory. Just shows you, you shouldn’t ignore the early researchers. They came up with some amazing studies which nowadays are often forgotten or ignored.
The synovial fluid
For those that are worried about the affect this process has on your joints, I can allay your fears. The synovial fluid is actually a lubricant which acts as a shock absorber so your bones don’t grind together. This lubricating fluid is kept in place by the synovial membrane. As long as the membrane is not damaged, your joints should be fine. If you want to know the real cause of arthritis and calcification condititions, check this article out!
No link with osteoarthritis in hands or knees
To date, research has shown no correlation between cracking and osteoarthritis in hands or other joints. A study showed that whether your hands cracked or not, there was no relation to the prevalence of the disease. The authors explained:
“Total past duration (in years) and volume (daily frequency x years) of knuckle-cracking (KC) of each joint type also was not significantly correlated with OA [osteoarthritis] at the respective joint. A history of habitual KC – including the total duration and total cumulative exposure, does not seem to be a risk factor for hand OA.”
That’s a relief, I will not worry now everytime I bend down and both my knees make a loud cracking noise. It’s still embarrasing though!
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