Are you a knuckle cracker?


Ever wonder why you need to crack your knuckles to find a sense of relief in your hand? I crack my knuckles occasionally, but it really freaks me out when people around crack them so loud to the point that I cringe at the sound. Your joints are where two of your bones meet, and they are covered with synovial fluid, a thick clear liquid. This liquid almost serves as a lubricant to your bones. You are literally pulling apart your joints when you crack your knuckles. Discovery Fit & Health states that "the connective tissue capsule that surrounds the joint is stretched. By stretching this capsule, you increase its volume." As many of you might know from science classes, volume and pressure are inverse meaning when one increases, the other decreases, and vice versa. "So as the pressure of the synovial fluid drops, gases dissolved in the fluid become less soluble, forming bubbles through a process called cavitation." The pressure in the capsule can drop very low if joints are stretched too far, causing the bubbles to burst. These bubbles bursting are the noise we hear when we crack our knuckles. The sound is a result of the "smooth cartilage and the roughness of the joint surface," according to The Library of Congress' Everyday Mysteries. It takes about 20-30 minutes for the gas to collect again in the joint fluid, and in that time you do not feel the need to crack your knuckles. Next time you crack your knuckles; observe how long it is before you feel the need to crack the same finger again.

According to Anatomy and Physiology Instructors' Cooperative, only one study has been conducted observing the possible harms of knuckle cracking. Raymond Brodeur conducted this experiment and published it in the Journal of Manipulative and Physiological Therapeutics. His control group was 300 knuckle poppers (control group...sound familiar from class?) Brodeur came to the conclusion that there is no relationship between knuckle popping and arthritis.

However, Advanced Physical Medicine reported that although cracking your knuckles does not cause arthritis, there is "a relationship between knuckle cracking and hand swelling, loss of lower grip strength, ligament damage, soft tissue injuries and dislocation of tendons." Although these symptoms are pretty harmless, if you really have been swayed not to crack your knuckles, there are other ways of relief. When I really need to crack my knuckles and don't want to, I often rotate my fingers in a circular motion while also rotating my wrist. Try it next time you feel the need to crack your knuckles. However, if you do feel pain in your hands when/after cracking your knuckles, you should stop and see a doctor about it.

From the Library of Congress' Everyday Mysteries, I also learned that there are two types of joints: a healthy joint and an osteoarthritic joint. In a healthy joint, the bones are surrounded by smooth cartilage. They are protected by a joint capsule lined with synovial fluid. Together, the capsule and the fluid protect the cartilage, muscles, and connective tissue. On the other hand, an osteoarthritic joint has damaged cartilage that has worn away over time."Spurs grow out from the edge of the bone, and synovial fluid increases," altogether causing the joints to feel stiff and sore.

Although you can not get arthritis from knuckle cracking, I often hear about so many elderly people having arthritis, including my grandma. I always thought that arthritis is only possible in older people. But after doing some research on the Arthritis Foundation website, I found out that there is such a thing as juvenile arthritis, which can occur in children about 16 and under. There are several types, the most common being juvenile idiopathic arthritis. The other types of possible juvenile arthritic include but are not limited to: Oligoarthritis, Systemic, Polyarthritis, and Enthesitis- related. Did anyone have the same misconception like me that arthritis was only apparent in older people? Back to joints, once a child is diagnosed with arthritis, the doctor constantly examines the amount of joints affected, as well as take blood tests.

I recently realized how much I take my health for granted. My grandma has pain when she reaches up to the cabinet to grab a plate. Such simple tasks such as that we take for granted. It takes us two seconds to lift our hand up and put it down. For people with arthritis, is a huge deal to reach your bones farther than you feel comfortable. That is why we should take good care of our health and bodies now; so that when we are older, we remain healthy and abled. Now, I don't think knuckle cracking will effect you much, but better not over-do it just to be safe!


Hi Paulina. I read your blog and I too am an avid knuckle cracker. I was wondering about what the long term effects are if I cracker other joints on my body: neck, back, elbows, knees, ankles. Because, I do crack those things sometimes. Does cracking your neck or back have any long term effects? I've read that rather than gas collecting like in your fingers, the joints in your spine collect fluid and it could be harmful to crack your neck. Do you know if this is true?

I have never been an "avid knuckle cracker," but I have yet to place my finger on exactly why this is. I was always told from a young age that cracking your knuckles would cause arthritis. My mom would always cringe at the sound and scold me for doing so. Even after I learned in science class that cracking your knuckles has no connection to arthritis, I still never developed the habit. In fact, I find cracking my knuckles very painful. I can't decide whether this is because it is actually painful or just because I still subconsciously think that it is harmful. I also still skeptical about it's harmlessness. Although some studies have said that it isn't harmful, I wonder if it's possible that we just haven't studied this behavior for a long enough period of time. Could this be like smoking? Could we discover years from now that cracking your knuckles really does contribute to arthritis or some other bone disorder?

Great post, I am a constant neck, back and especially wrist cracker so this question hits home. After reading your article and doing some research on my own, I am relieved that there are no proven negative health effects of the habit. I have two comments.

First according to the John's Hopkin's Ortho website your explaination for handcracking noise is indeed a prevailing theory, it is one of a few which haven't been "proven". The website says, "Strangely enough the exact reason joints pop and snap is not totally understood." and gives another possible explaination for it, saying: " One theory is that the ligaments (tethers that hold the bones together) make these noises as they get tight rapidly when the joint is moving. In some instances, popping may be due to a tendon snapping over or around the joint."


I'm very interested in the matter as I noticed over the last few years as I've become an avid long-distance runner, that I now feel the need to crack my joints more often especially around my wrists. I wonder if there is any evidence that excercise increases the need to crack...

I have always heard that cracking your knuckles may lead to arthritis. I am an avid knuckle cracker and before reading this article I did crack my knuckle and I felt somewhat ashamed that I did. I think that from now on I will stop cracking my knuckles and I will follow your advice on what to do when I feel like cracking it. The urge to do so has arise so as I am writing this response, your advice will be very helpful.

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