I remember when I was a kid, I was told that you shouldn’t crack your knuckles because it causes arthritis. I’ve since noticed that cracking not just my knuckles but lots of joints throughout my body with spontaneous stretching and yoga-like movements makes me feel good subjectively and helps me fall asleep.
This made me wonder, what does the scientific literature say about the risks of joint cracking?
So the literature seems pretty unanimous that knuckle cracking (and probably joint cracking in general) does not cause arthritis. In fact, not only is there no evidence that joint cracking causes arthritis, several studies have found knuckle cracking actually correlates with a lower risk of arthritis.1 2
In one study of 135 patients who had arthritis and 80 people who did not, 18.1% of people who often cracked their knuckles had osteoarthritis, whereas 21.5% of people who did not crack their knuckles had osteoarthritis (for those who want to know, the p value of this inverse association was .548, so it wasn’t statistically significant).
So there were actually more people who almost never cracked their knuckles and yet had arthritis than there were people who did crack their knuckles and had arthritis. In the author’s own words:1
When examined by joint type, KC was not a risk for osteoarthritis in that joint. Total past duration (in years) and volume (daily frequency x years) of KC of each joint type also was not significantly correlated with osteoarthritis at the respective joint.
So it’s pretty unlikely that knuckle cracking causes arthritis.
Dr. Mercola has cited the same paper to show that joint cracking does not cause arthritis. Nevertheless, he advises us against joint cracking. He voiced concerns that joint cracking may lead to weakened grip strength and excessively relaxed and stretched out ligaments. He cites a paper showing that lowered grip strength and hand soreness were more common in people who cracked their knuckles than those who did not.2
However, it’s important to remember that this just showed a correlation between joint cracking and those symptoms, and correlation does not prove causation. Just as probable is that some uncontrolled for variable or condition that causes hand soreness and weak grip may also be causing people to feel like cracking their knuckles more often.
Protopapas et al. speculate that:
If one were to consider the anatomic and physiologic models solely, one could assume that maintaining motion throughout the joint could lower the likelihood of developing osteoarthritis.
On the other hand, the excessive use of a joint could lead to laxity of the ligaments supporting the joint, causing hypermobility or introducing an unnecessary stress that could eventually cause dysfunction.
Dr. Mercola cites what is referred to on his website as a “paper” he coauthored 20 years ago speculating the same thing. The term paper implies that it’s a scientific paper that’s been peer-reviewed and presents scientifically rigorous evidence. This paper is indexed on PubMed, but there is no abstract or link to the paper on the publisher’s website.3
UPDATE: I got my hands on a copy of Dr. Mercola’s so-called paper, and it turns out it’s not a paper at all. It’s a brief letter to the editor only a few paragraphs long, so it’s not peer-reviewed. All it says is that while a specific neck cracking technique is generally very useful, two of their patients developed neck discomfort, and they assumed neck cracking was the culprit. This is about as scientifically rigorous as saying that your best friend’s aunty May said it so it must be true. As my cancer biology professor would say, that’s not science, and it’s not admissible as evidence in a scientific search for the truth.
What’s more, there’s some evidence to suggest that joint cracking may even be beneficial for human health. Brodeur suggests that:4
Because the sudden joint distraction during a manipulation occurs in a shorter time period than that required to complete the stretch reflexes of the periarticular muscles, there is likely to be a high impulse acting on the ligaments and muscles associated with the joint.
This is an important conclusion, because others have proposed that reflex actions from high threshold periarticular receptors are associated with the many beneficial results of manipulation.
In other words, joint cracking triggers a reflex for the muscles to tense up and snap back into place. Quickly stretching any muscle triggers this stretch reflex, as it’s called. But the joint cracking occurs so quickly that the reflex, as fast as it is, is unable to stop it from happening. As a result, the impulse is sent very strongly through the nearby nerves. Others have suggested that the beneficial effects of musculoskeletal manipulations like those used in chiropractic and osteopathic medicine may be brought about in part by receptors near joints that sense intense mechanical stimuli like joint cracking.
Apart from chiropractic medicine and osteopathic manipulations, there are many practices you can do with the help of YouTube videos or in a class that incorporate lots of joint cracking, including several kinds of yoga, stretching, and pilates to name a few.
Personally, I’ve found that by practicing awareness of my body and how it feels, I can spontaneously and instinctively stretch and do yoga-like movements that crack many joints throughout my body. This practice relaxes me, makes me feel calmer and more at peace, and helps me fall asleep faster at night.
I like this spontaneous movement because it’s guided by what my body instinctively feels like it needs, rather than a generic one-size-fits all formula or someone else’s educated guess about what it needs.
I prefer the spontaneous method because I believe in the wisdom of the body. I believe the human body usually knows what it needs to maintain homeostasis and communicates this to conscious awareness through feelings and intuition. However, all these are excellent options and some will work better for some people than others.
Also worth noting is that all these joint cracking movement modalities have other benefits too. For instance, moving and stretching the body circulates the lymph system, which helps the body detoxify and protect you against infections.
- Deweber K, Olszewski M, Ortolano R. Knuckle cracking and hand osteoarthritis. J Am Board Fam Med. 24(2):169-174. doi:10.3122/jabfm.2011.02.100156.
- Castellanos J, Axelrod D. Effect of habitual knuckle cracking on hand function. Ann Rheum Dis. 1990;49(5):308-309. http://www.ncbi.nlm.nih.gov/pubmed/2344210. Accessed November 27, 2016.
- Earl DT, Mercola JM. Cracking down on “neck cracking”. Am Fam Physician. 1992;45(2):452, 459. http://www.ncbi.nlm.nih.gov/pubmed/1739036. Accessed November 27, 2016.
- Brodeur R. The audible release associated with joint manipulation. J Manipulative Physiol Ther. 1994;18(3):155-164. http://www.ncbi.nlm.nih.gov/pubmed/7790795. Accessed November 27, 2016.