Many of us have been warned against cracking our joints if we wish to avoid getting arthritis. Emmet Feerick investigates the source of that cracking sound, and whether joint-cracking causes arthritis.
For many it brings satisfaction, and for others it is nails-on-a-chalkboard cringe-inducing. Knuckle-cracking is a touchy subject, and whether or not you engage in this activity yourself, you have likely heard that it can damage your joints. This seems plausible; surely nothing good can come of bending your joints to the cracking point. One imagines two bones pressing against each other until one slips over the other, snapping off shrapnel from both. If such a thing were what happened, then cracking your joints would indeed cause damage. Fortunately for many, this does not appear to be the case.
The space between our joints is filled with a viscous liquid called synovial fluid. Its function is to reduce the friction between our bones when we move. Dissolved in this fluid are small amounts of nitrogen and carbon dioxide. Research has shown that when you stretch your joints by pulling or bending them, you increase the space within the joint, lowering the pressure. This causes the dissolved gases to come out of solution and form a bubble, which then promptly collapses.
“A 2015 study involving video MRI suggests that the noise is created when the bubble is formed, and not when it collapses.”
Traditionally, research into joint-popping has been carried out by chiropractors and physiotherapists. The consensus in these fields has long been that the cracking noise is a result of the collapse of the bubble and the return of the joint to its normal position. However, a 2015 study involving video MRI has shown that the noise is created when the bubble is formed, and not when it collapses. The authors of this study reached this conclusion after closely monitoring the audio and video of the joint cracking, and linking the timing of the “cracking” noise to the moment of the bubble’s formation.
“A large 2011 study of 215 people aged 50 to 89 found no link between knuckle-cracking and osteoarthritis”
The discovery that this sound is caused by bubbles and not bones is good news for knuckle-crackers. It is the likely reason that decades of study into the subject have yielded no evidence that cracking your joints causes arthritis. A large 2011 study of 215 people aged 50 to 89 found no link between knuckle-cracking and osteoarthritis regardless of how many years the participants had been cracking their knuckles for, or how frequently. Countless other studies have found similar results. One study found that chronic knuckle-cracking is associated with poorer grip strength and swollen hands, though this has been less well-corroborated.
The moral: cracking your knuckles will not give you arthritis, but it may cost you the strength of your grip, and the patience of some friends.