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Is it Harmful to “Crack” Your Knuckles?

(last updated 5/30/20)

We all know someone who loves to habitually crack their knuckles. Most of us have at least tried it a few times. If you are good at it, the sound can be quite impressive…although some might just call it annoying! Perhaps your mother told you it would end up causing arthritis, but is that true? Is something breaking inside those knuckles?

The cracking or popping sound made when you deliberately stretch your fingers is usually caused by a process called cavitation. Cavitation occurs when a joint is stretched, causing negative pressure in the joint which pulls nitrogen gas out of the joint fluid. When these bubbles partially collapse, it causes a popping sound. Interestingly, this phenomenon was only finally confirmed in 2015 by researchers who used MRI to visualize the nitrogen bubbles forming in the finger joints. A less common source of popping noise occurs when some people move their fingers in a certain way that causes sudden snapping of tendons or ligaments over the underlying bones which may produce a similar sound.

There is no evidence that cracking your knuckles causes arthritis. One dedicated researcher named Donald Unger went so far as to routinely pop his own knuckles, but only in one hand for 60 years. He found no difference in his x-rays comparing one hand to the other after a lifetime of cracking knuckles in just the one hand. Another research study suggested that cracking knuckles may reduce grip strength, but a more recent study found no difference in strength. There have been a few case reports of finger dislocations and ligament injuries from overzealous knuckle cracking, but these injuries seem to be rare. The bottom line is that while knuckle cracking may be annoying, it is not likely to be harmful.

There are some “clicks and pops” in the hand that do signal concern for a more significant problem. Any time these hand noises are associated with pain or stiffness, you should seek medical attention. The most common painful source of popping is a condition called trigger finger in which the flexor tendon of the finger can become swollen and catch on the tendon sheath, sometimes causing the finger or thumb to lock up in a flexed position. Painful clicks and pops in the wrist may be due to ligament injuries or arthritis. Orthopaedic Hand and Wrist Surgeons specialize in diagnosing and treating these problems with both operative and nonoperative treatments available.

Eric Angermeier, MD
Orthopaedic Hand and Wrist Surgeon