Does Cracking Your Knuckles Increase Your Risk Of Arthritis?

A popular factoid, often told to those who like to crack their knuckles, is that cracking your knuckles repeatedly will cause arthritis years down the road. Is there any truth or scientific backing to this claim?

Does Cracking Your Knuckles Increase Your Risk Of Arthritis?

The short, simple answer is ‘no’, as there is no scientific evidence to back up the claim. Quite the contrary. The most recent study examined the hand radiographs of 215 people (50 to 89 years of age) and compared them. They compared the sets of those who regularly cracked their knuckles to those who did not and found that knuckle-cracking did not cause hand osteoarthritis, no matter how often or for how long a person had cracked their knuckles.

Other Risks

This does not mean knuckle-cracking is perfectly safe, however. Another study concluded that while there was no increased risk of arthritis in the hands of chronic knuckle-crackers, people who cracked their knuckles habitually were more likely to have hand swelling due to inflammation and up to a 25% reduction in grip strength.

So what does cause arthritis then? There are many different kinds of arthritis, over 100 different types. The most common among them, osteoarthritis, is caused by simple age and genetics. If you X-ray the hands of people age 65 or older, 70% will have arthritis, with the osteoarthritis tending to be worse in the dominant hand.

Where Does The ‘Popping’ Or ‘Cracking’ Sound Come From?

Synovial fluid (a viscous, non-Newtonian fluid found in the joints and acts as a lubricant) has dissolved oxygen, nitrogen, and carbon dioxide within it. When pressure is applied to a joint, the area inside the joint capsule expands. However, the expansion is limited by how much fluid is contained in the joint. At some point, the pressure becomes to much and the cracking sound you hear comes from the dissolved gases rapidly being released from the synovial fluid.

References:
- Castellanos J. Axelrod D. “Effect of habitual knuckle cracking on hand function.” Annals of the Rheumatic Diseases. 49(5):308-9, 1990
- Mirsky, Steve (December 2009). “Crack Research: Good news about knuckle cracking.“. Scientific American.
- Brodeur R: “The audible release associated with joint manipulation.” Journal of Manipulative & Physiological Therapeutics. 18(3):155-64, 1995