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Why Do People Crack Their Knuckles & Is It Bad For You?

Knuckle cracking is a common behavior, and a lot of people enjoy cracking their knuckles from time to time. Over time, it can become a habit or even a way to deal with stress or anxiety. Many also describe it as a way of releasing the tension, while others simply like to crack their knuckles. While there hasn’t been much research on what the effects of knuckle cracking are, but the limited amount of research that is there indicates that it does not cause any harm to your joints. If you want to find out about why some people crack their knuckles, and if it is bad for you, here is everything you need to know on this fascinating topic.

Overview of Knuckle Cracking

Knuckle cracking is a common behavior that many people indulge in. While some people crack their knuckles when they are stressed or bored, others just do it out of habit.(1,2,3) There are many myths associated with knuckle cracking, the most common one being that it can cause arthritis. While there is not much research that has been done on the effects of knuckle cracking, but whatever little evidence is there, it indicates that knuckle cracking does not harm your joints. According to a review in the Swiss Medical Journal, no evidence was found in any of the studies that showed that cracking your knuckles can cause arthritis.(4,5,6)

Another case involved a doctor who showed that knuckle cracking does not cause arthritis by experimenting on himself. He reported that over a period of 50 years, he continued to crack his knuckles on his left hand at least two or more times in a day and never cracked his knuckles on the right hand. At the end of the experiment, the knuckles on the left hand showed no difference from the ones in the right hand. Neither hand had any signs or symptoms of arthritis.(7)

At the same time, there is also no evidence that shows that cracking your knuckles can make the joints larger or weaken the joints. Neither does it have any impact on the strength of your grip.

Why Do People Crack Their Knuckles?

Studies have found that nearly 54% of people regularly crack their knuckles.(8) Various studies showed that people do it for many reasons, some of which include:

  • Nervousness: Similar to twirling your hair or wringing your hands, cracking your knuckles is a common way to keep the hands occupied when you are feeling nervous.
  • Liking The Sound It Makes: Many people simply enjoy listening to the sound knuckle cracking makes.
  • Stress: Many people who are stressed like cracking their knuckles. It gives them a diversion, and they feel they get a release from their stress without causing harm to anything.
  • The Way It Feels: Many people think that cracking their knuckles actually creates more space in the joint, thus relieving tension and increasing mobility. However, even though it may feel like there is room, but there is no evidence to show that there is any space created.
  • Habit: Many people simply develop a habit of cracking their knuckles. Regardless of whatever the reason, you start cracking your knuckles, but it is easy to continue doing it till a point when you do it without even thinking about it. When you begin to unconsciously crack your knuckles several times a day, you know that it has become a habit. People who crack their knuckles up to five or more times in a day are known as habitual knuckle crackers.

What Makes The Pop Sound When You Crack Your Knuckles?

As mentioned above, many people like listening to the pop or cracking sound that comes when you pull your knuckles. The reason behind why the joint makes this popping or cracking noise is not clearly understood. For a long time, this popping sound was believed to come because of nitrogen bubbles that either formed or collapsed in the joint fluid. Another belief was that it came from the movements of the ligaments around that knuckle.

However, in 2015, a study was carried out that observed the knuckles while they were being cracked under an MRI. The MRI found that a cavity formed because of the negative pressure that was created due to the joint being pulled apart quickly. The researchers determined that the popping sound was made by the formation of this cavity. However, they could not find any explanation behind the loudness of the sound.(9)

Another study in 2018 suggested that the popping sound was made due to the partial collapse of the cavity.(10) A review of various studies was carried out, and it found that it took around 20 minutes for the cavity to completely collapse in order for a new cavity to form. This is also believed to be the reason why once you crack your knuckles, it is not possible to immediately do it again.(11)

Are There Any Side Effects To Cracking Your Knuckles?

Generally, cracking your knuckles should not be a painful exercise. It should not cause swelling or any change to the shape of the joint. If you are experiencing any of these symptoms when you crack your knuckles, this could be an indication that some other problem is there.

Even though it happens rarely, but if you end up pulling hard enough, you can actually manage to pull your finger out of the joint or cause serious injury to the ligaments around your joints.

If you find that your joints have become swollen or painful while you are cracking your knuckles, it is most likely because of an underlying medical condition, like gout or arthritis.(12,13)

How To Stop Cracking Your Knuckles?

Even though knuckle cracking is unlikely to harm you, but it might be distracting and irritating to the people around you. If it becomes a habit, you may find it difficult to stop.

Here are some tips that may help you break the habit of knuckle cracking:

  • If you crack your knuckles as a way to relieve stress, try alternative solutions like exercise, meditation, or deep breathing.
  • Think about why you are cracking your knuckles and deal with any underlying issues that come up.
  • Try to be aware of the times you are cracking your knuckles and try to consciously stop yourself.
  • Keep your hands occupied with other stress relievers, such as using a stress ball or rubbing a worry stone.
  • Try wearing a rubber band on your wrist and snap the band whenever you are about to crack your knuckles.


Cracking your knuckles does not cause harm. It also should not cause pain, swelling, or change the shape of the joint. If any of these happen, it is an indication that something is wrong, and you need to be checked out by a doctor.

However, if you pull your finger very forcefully or move it in the wrong direction, you can cause injury to your finger, which can be very painful. You may also notice that your finger starts to look crooked or develops swelling. In such a case, you should see a doctor right away. You should also see your doctor if you find your joints are swollen or painful when you crack your knuckles. This is usually an indication that there is an underlying condition that needs to be checked out by a doctor.

Nevertheless, research shows that cracking your knuckles is not harmful and neither does it cause arthritis or change the shape of your joints. It can be distracting to the people around you. If cracking your knuckles has become a habit, it can be difficult to stop the practice, but it can be done. The first step is to be aware of when you are doing it and stop yourself. Finding other ways to relieve stress, like squeezing a stress ball, can also help you break the habit.


  1. Castellanos, J. and Axelrod, D., 1990. Effect of habitual knuckle cracking on hand function. Annals of the rheumatic diseases, 49(5), pp.308-309.
  2. Swezey, R.L. and Swezey, S.E., 1975. The consequences of habitual knuckle cracking. Western Journal of Medicine, 122(5), p.377.
  3. Boutin, R.D., Netto, A.P., Nakamura, D., Bateni, C., Szabo, R.M., Cronan, M., Foster, B., Barfield, W.R., Seibert, J.A. and Chaudhari, A.J., 2017. “Knuckle Cracking”: Can Blinded Observers Detect Changes with Physical Examination and Sonography?. Clinical Orthopaedics and Related Research®, 475(4), pp.1265-1271.
  4. Saubade, M., Karatzios, C., Léonard, E., Besson, C., Gremion, G. and Gremeaux, V., 2017. «My joints are cracking, is it serious doctor?» A review about sounds produced by joints. Revue medicale suisse, 13(569), pp.1334-1338.
  5. Yildizgören, M.T., Ekiz, T.İ.M.U.R., Nizamogullari, S., Turhanoglu, A.D., Guler, H., Ustun, N., Kara, M.U.R.A.T. and Özçakar, L.E.V.E.N.T., 2017. Effects of habitual knuckle cracking on metacarpal cartilage thickness and grip strength. Hand Surgery and Rehabilitation, 36(1), pp.41-43.
  6. Gaetano, J., 2009. Cracking the Cracked Knuckle: A Medical Student’s Take. The Journal of rheumatology, 36(11), pp.2624-2624.
  7. Onlinelibrary.wiley.com. 2021. Does knuckle cracking lead to arthritis of the fingers?. [online] Available at: <https://onlinelibrary.wiley.com/doi/epdf/10.1002/1529-0131%28199805%2941%3A5%3C949%3A%3AAID-ART36%3E3.0.CO%3B2-3> [Accessed 25 February 2021].
  8. Deweber, K., Olszewski, M. and Ortolano, R., 2011. Knuckle cracking and hand osteoarthritis. The Journal of the American Board of Family Medicine, 24(2), pp.169-174.
  9. Kawchuk, G.N., Fryer, J., Jaremko, J.L., Zeng, H., Rowe, L. and Thompson, R., 2015. Real-time visualization of joint cavitation. PloS one, 10(4), p.e0119470.
  10. Suja, V.C. and Barakat, A.I., 2018. A mathematical model for the sounds produced by knuckle cracking. Scientific reports, 8(1), pp.1-9.
  11. Protopapas, M.G. and Cymet, T.C., 2002. Joint cracking and popping: understanding noises that accompany articular release. The Journal of the American Osteopathic Association, 102(5), pp.283-287.
  12. Swezey, R.L. and Swezey, S.E., 1975. The consequences of habitual knuckle cracking. Western Journal of Medicine, 122(5), p.377.
  13. Gaetano, J., 2009. Cracking the Cracked Knuckle: A Medical Student’s Take. The Journal of rheumatology, 36(11), pp.2624-2624.

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Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:March 25, 2021

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