Ask a Scientist: Does cracking your knuckles cause arthritis?

By: Kylia Goodner

We all crack our knuckles (or at least know someone who cracks theirs), but each time we hear the characteristic “pop” of a joint cracking we have a slight moment of panic. Were our parents correct? Will cracking our knuckles cause arthritis?

Before I answer the question, I want to explain what is causing the characteristic “pop” associated with knuckle or joint cracking. Surrounding all of the body’s joints is a liquid called “synovial fluid” that helps your joints move smoothly. When oxygen and other gasses are brought into this area, large gas bubbles are formed. When you move or extend your fingers this lengthens the space between your joints and decreases the pressure formed by the fluid. This sudden decrease in pressure causes the large gas bubbles to “pop” and form into extremely tiny bubbles. Over the course of the next fifteen minutes the space between your joints returns to normal, which allows for another round of popping.

But does this repetitive cracking cause arthritis?  Although there have only been a handful of studies examining knuckle cracking, the prevailing answer is no.  A study examining 215 patients, found no increase in the amount of arthritis between knuckle crackers and non-knuckle crackers.  Another study examining 300 patients found the same result. However, this doesn’t mean its good for you or your hands. This same study found that knuckle cracking is associated with increased hand swelling and decreased grip strength.

As in every scientific study there are critiques. To date, there hasn’t been a single study to examine knuckle-crackers under the age of 45. Now, although it is probably safe to assume that people cracking their knuckles at age 45 have been doing it for most of their lives, a study examining knuckle cracking over time hasn’t been performed.  But for now, whenever you hear that characteristic “pop” you can quiet the terrified voice in the back of your mind and know that it is unlikely to cause arthritis!