# Cracking your knuckles does not cause arthritis

> **Verdict: False** · evidence strength 90/100 · claim checked
> Decades of studies, including one man's 60-year experiment on his own hands, find no link between knuckle cracking and arthritis.

Published September 14, 2026 by FactsReef (Health). Canonical: https://factsreef.com/fact-checks/health/cracking-your-knuckles-does-not-cause-arthritis-e32630
Asked as: "Does cracking your knuckles cause arthritis?"

## The short answer
No study has found that habitual knuckle cracking causes osteoarthritis or rheumatoid arthritis, and several have looked [1, 2]. The sound is a gas bubble forming in the fluid that lubricates the joint, not bone grinding on bone [3]. The strongest thing that can be said against the habit is that a couple of small studies linked heavy cracking with hand swelling or a weaker grip, and later work failed to confirm even that [1].

## What actually makes the sound
Finger joints are sealed capsules filled with synovial fluid. When you pull or bend a knuckle past its normal range, the capsule expands, pressure inside falls, and dissolved gas comes out of solution as a bubble. In 2015 a team at the University of Alberta filmed the process inside an MRI scanner and showed the pop coincides with the sudden formation of a cavity in the fluid, not its collapse [3]. The joint then needs roughly 20 minutes to re-absorb the gas, which is why you cannot crack the same knuckle twice in a row [3, 4].

## The 60-year experiment
The most famous piece of evidence is also the simplest. Donald Unger, a physician in California, cracked the knuckles of his left hand at least twice a day for more than 60 years and left his right hand alone. In a 1998 letter to the journal *Arthritis & Rheumatism* he reported no arthritis in either hand and no difference between them [2]. It is a sample size of one, but it is a remarkably clean one, and it earned him an Ig Nobel Prize in 2009 [4].

## What the larger studies found
- A 1990 study of 300 people aged 45 and over found no more arthritis among knuckle crackers than among non-crackers, though it did report more hand swelling and lower grip strength in the cracking group [1, 4].
- A 2011 study of 215 people, which compared X-rays of the hands with self-reported cracking habits, found no association between cracking and osteoarthritis in any joint, however long or often people had done it [1, 4].
- Reviews by hand surgeons and rheumatologists since then have reached the same conclusion: the habit is harmless to the joint itself [1].

The grip-strength and swelling findings from 1990 have not been replicated and are generally treated as a curiosity rather than a warning [1].

## Why the myth persists
The pop sounds like something breaking, and osteoarthritis is common in the hands of older adults, so the two are easy to connect in the mind. Parents also have an obvious motive to discourage a noise that annoys them. But arthritis in the fingers is driven mostly by age, genetics, previous injury and occupation, not by the cavitation of joint fluid [1, 4].

## Frequently asked questions

### Can cracking my knuckles hurt me in any other way?

Case reports describe rare injuries from forcing a joint, such as a dislocated finger or a strained ligament, but they involve unusual force rather than the everyday habit [4]. If cracking is painful or a joint feels unstable, that is a reason to see a clinician.

### Is it different for the neck or back?

The mechanism is the same gas bubble, but the neck contains arteries and nerves that fingers do not. Cracking your own neck gently is not linked to harm; forceful manipulation carries small, documented risks that the finger joints do not [4].

### Does the habit make joints looser over time?

There is no evidence that it stretches the joint capsule or ligaments permanently. Joints feel briefly more mobile after a crack because of the change in pressure, and the feeling passes within minutes [3].


## Sources

1. [Knuckle cracking: Annoying and harmful, or just annoying?](https://www.health.harvard.edu/blog/knuckle-cracking-annoying-and-harmful-or-just-annoying-2018051413797) — Harvard Health Publishing, May 2018
2. [Does knuckle cracking lead to arthritis of the fingers?](https://pubmed.ncbi.nlm.nih.gov/9588729/) — Arthritis & Rheumatism via PubMed, 1998
3. [Real-Time Visualization of Joint Cavitation](https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470) — PLOS ONE, April 2015
4. [Cracking joints](https://en.wikipedia.org/wiki/Cracking_joints) — Wikipedia

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