Mythbuster: Cracking Your Knuckles Cause Arthritis
You’ve heard it a million times. The satisfying pop of a knuckle is almost always followed by a concerned onlooker warning, "You're going to get arthritis if you keep doing that!" It's a piece of advice passed down through generations, but does it hold any scientific weight?
Let's bust this myth.
The Truth: No Link Between Knuckle Cracking and Arthritis
Rest easy, knuckle-crackers. The verdict from the medical community is overwhelmingly clear: Cracking your knuckles does not cause arthritis. Decades of research have failed to find any credible link between this common habit and the development of joint disease.
So, what’s actually making that popping sound? It’s not your bones grinding together. Your joints contain a lubricating substance called synovial fluid, which acts like oil in an engine. This fluid is filled with dissolved gases, primarily nitrogen.
When you stretch or bend your finger to crack the knuckle, you pull the joint apart. This creates negative pressure, causing the dissolved gases in the synovial fluid to rapidly form a bubble. The "pop" you hear is the sound of that gas bubble collapsing. This process is known as cavitation. Once you've cracked a knuckle, you can't crack it again right away because it takes about 20 minutes for the gases to re-dissolve into the fluid.
Busting the Myth
The most famous piece of evidence against this myth comes from a doctor who dedicated his life to it—literally. Dr. Donald Unger cracked the knuckles on his left hand every day for over 50 years, but he never cracked the knuckles on his right hand. He used his right hand as a control group. The result after six decades? There was no arthritis in either hand, and no noticeable difference between them. His dedicated (and slightly eccentric) study earned him the 2009 Ig Nobel Prize in Medicine.
So, Is It Totally Harmless?
For the most part, yes. While the habit doesn't cause arthritis, some studies have noted a possible correlation between chronic, long-term knuckle cracking and other minor issues, such as slightly reduced grip strength or soft tissue swelling in the hands. However, these findings are not consistent across all studies. There have also been very rare, isolated reports of people injuring themselves by using excessive force to crack their joints, leading to ligament damage or dislocations.
The biggest downside to cracking your knuckles? It can be an annoying sound to the people around you.
Why It Matters
Understanding the science behind this myth is about more than just justifying a noisy habit. It’s a great example of how medical folklore can persist for generations without any scientific backing. By separating fact from fiction, we can stop worrying about harmless habits and focus on the real risk factors for conditions like arthritis, such as age, genetics, and injury.
Bottom Line
The idea that cracking your knuckles will lead to arthritis is a myth. The popping sound is simply the collapse of a gas bubble in your joint fluid, not the grinding of bone on bone. Extensive research and one very dedicated doctor have shown that there is no connection between the habit and joint disease. So, while it might not win you any friends, you can be confident it won't ruin your joints.
Did you miss our July MythBuster? Check out Mythbuster: Goldfish has a 3-second memory. And stay tuned, next month we’ll bust another common myth you might still believe!