Is It Bad to Crack Your Knuckles?

by James C. McIntosh, MD, Lexington Orthopaedics and Sports Medicine

If you're a frequent knuckle cracker, a family member or friend has likely told you that it's going to cause arthritis. But is this widely held belief true? Let's break down the facts behind the snap, crackle, and pop of knuckle cracking.

What Causes the Sound?
When you crack your knuckles, the popping sound comes from releasing gas bubbles in the synovial fluid—the lubricating liquid in your joints. Pulling or bending your fingers creates negative pressure in the joint, which allows dissolved gases like carbon dioxide to form bubbles. These bubbles collapse rapidly, making the distinctive sound.

Studies have shown that it takes about 20 minutes for the gases to re-dissolve into the fluid, so you can't repeatedly crack the same joint in quick succession.

The Myth of Arthritis
The most common concern about knuckle cracking is that it can cause arthritis. However, there is no solid evidence to support this claim. A notable study conducted by Donald Unger, MD, who cracked the knuckles of one hand for over 60 years while leaving the other hand untouched, found no difference in arthritis development between the two hands.

Additionally, broader research studies have not found a link between habitual knuckle cracking and an increased risk of arthritis. Osteoarthritis, the most common form of arthritis, is typically caused by factors such as age, genetics, joint injuries, and repetitive strain, none of which are associated with knuckle cracking.

Potential Downsides
While knuckle cracking doesn't cause arthritis, it's not entirely without risk. Excessive or aggressive cracking can lead to soft tissue damage, reduced grip strength, or joint swelling over time. These cases are rare but worth considering if you habitually crack your knuckles.

The Psychological Factor
For many, cracking knuckles is a habitual or stress-relieving behavior. The action can provide a sense of satisfaction or serve as a mental reset. While not inherently harmful, it's always good to evaluate whether the habit is tied to underlying stress or anxiety and find healthier alternatives.

The Bottom Line
Cracking your knuckles is generally harmless and won't lead to arthritis. However, like any repetitive action, moderation is key. If you're concerned about joint health, focus on maintaining a balanced diet, staying active, and avoiding repetitive strain on your hands and wrists.


James C. McIntosh, MD, Lexington Orthopaedics and Sports Medicine