Have you ever heard someone cracking their knuckles and wondered whatā€™s causing the ā€œpoppingā€ sound? Ā Hint: it has to do with your joint capsule, a fluid-filled connective tissue container that surrounds and contains your joint.Ā  The fluid inside contains gases including oxygen, nitrogen and carbon dioxide.Ā  When you stretch of pull your joint beyond its normal range of motion, the pressure inside the joint capsule changes, creating a vacuum effect and causing a gas bubble to form and burst with a ā€œpopā€!

Another, much less amusing and more serious cause of joint popping is because something (like a torn or loose piece of knee cartilage) is caught between the joint surfaces.Ā  When this happens, sometimes the knee can lock with a loud ā€˜popā€™. Once a joint is stuck like this, it may need to be jostled around to free the object that is stuck ā€“ and when it is dislodged it can cause another pop. Ā Ew.

What you probably REALLY wanted to know though ā€“ was whether your mom was right when she said you shouldnā€™t crack your knuckles.Ā  And of course she was right!Ā  Sheā€™s always right, isnā€™t she? Studies have shown that knuckle cracking is related to hand swelling, lower grip strength and damage to the ligaments that surround the joint.Ā  And if you stop to think about it, when is it ever a good idea to forcefully tug your joints beyond their natural end range?Ā *crickets*

You never actually NEED to crack your knuckles, but you might sometimes feel like stretching your hands and fingers.Ā  Next time you get the urge to crack your knuckles, try this Yoga Tune UpĀ® wrist stretch instead.

This article is part 4 of a 4-part series on interpreting sounds from the joint space.Ā 

Enjoyed this article? Read Snap, Crackle and Pop ā€“ Part III: Crackle and CrepitusĀ 

 

Sources

Nichols, Hannah.Ā  ā€œWhy do knuckles and joints crack? Can cracking joints cause arthritis?ā€ Medical News Today. February 3, 2015.

Everyday Mysteries.Ā  Fun Science Facts from the Library of Congress.Ā  ā€œWhat causes the noise when you crack a joint?ā€Ā  Retrieved from http://www.loc.gov/rr/scitech/mysteries/joint.html. February 3, 2015.

Matsen, Frederick A. III, MD. ā€œJoints.ā€ UW Medicine.Ā  www.orthop.washington.edu

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