Does Cracking Your Knuckles Really Cause Arthritis? What Science Says

Knuckle crackers have heard the same warning: Stop or you'll pay for it with arthritis later. However, the research on that claim is more reassuring than many people expect, with a few caveats worth knowing.

Whether it happens at a desk, on the couch, or in the middle of a conversation, a cracking knuckle rarely goes unnoticed. It's a habit many people share, and it raises a fair question about what it does to the joints over time. To answer it, let's start with what arthritis actually is.

What Is Arthritis?

Arthritis is a disease that damages joints, the junctions where two bones meet. Many people develop it from ordinary wear and tear over time, while others develop it following a joint injury or as a complication of underlying health conditions.

Any joint can be affected, but it shows up most often in the hands and wrists, knees, hips, feet and ankles, shoulders, and lower back.

What Did the Studies Find?

So does knuckle cracking set the stage for it? Probably not. Several studies compared rates of hand arthritis in habitual crackers with rates in people who never crack, and the habit didn't appear to raise the risk. That may come as a relief to anyone who has been told to stop.

The sound itself comes from gas bubbles forming and popping within synovial fluid, the liquid that keeps joints lubricated. Pulling the bones apart, either by stretching the fingers or bending them backward, creates negative pressure, and the bubbles pop.

The authors of one study compared the burst of vibrating energy to "the forces responsible for the destruction of hydraulic blades and ship propellers."

Why Do People Do It?

Cracked knuckles tend to feel looser and move more freely for a while afterward, which makes the habit rewarding and explains why the urge keeps coming back.

For others, the habit begins in childhood when they find the popping sound amusing and repeat it until it hardens into a routine.

Reasons to Ease Up Anyway

Skipping the arthritis worry doesn't make the habit risk-free. After many years, habitual crackers may have weaker grip strength than people who don't crack.

The medical literature also contains a few reports linking knuckle cracking to injuries, including damage to the ligaments around a joint and dislocated tendons, the attachments that connect muscle to bone. Those cases improved with conservative treatment.

What Really Causes Arthritis?

Doctors sort arthritis into two main categories. Inflammatory types, such as rheumatoid arthritis, differ from degenerative arthritis, better known as osteoarthritis or wear-and-tear arthritis.

The exact causes of both remain unclear, and research is still working out how they develop. A genetic predisposition is highly likely in each case. For the inflammatory types, an unknown environmental exposure may also play a part.

For wear-and-tear arthritis, aging and heavy mechanical stress may speed up joint damage, as in the knees of older people who are obese and genetically predisposed.

In short, the evidence points away from knuckle cracking as a cause of arthritis. Genes, age, and stress on the joints appear to matter far more, and grip strength is a better reason to ease up on the habit.