I’ve been cracking my knuckles for years. Whenever I did it around my mom as a little kid, she would get mad at me and tell me that it’ll give me arthritis someday. Now, I’ve come to the realization that she didn’t really have any evidence to prove that claim, and she also most likely told me that to scare me and get me to stop. But lately, I’ve been wondering whether or not I should try to break the habit that I’ve been told is so harmful.
The first question to ask is what it is that makes the cracking noise. Tina Hesman Saey of ScienceNewsforStudents (2015) writes that the cracking noise comes from a bubble in between the joints in the finger. The original data comes from a study performed in 1947 that showed the two joints in the finger rapidly separating and forming an air bubble. Since then, different hypotheses have been suggested, including a theory that claimed that the noise came from the bubble itself popping. But recently, two scientists from the University of Alberta in Canada decided to do an MRI of a hand while the knuckle is being cracked. The official study showed that the noise comes from a cavity in the knuckle joint popping. The cavity was formed by fluid rushing to the knuckle. The results were in line with previous thinking, but now, there was actual scientific data to back up the theories. The study concluded with a statement about how the scientists plan to repeat their study in the future with bigger sample sizes, including individuals who are unable to crack their knuckles.
The image above shows the cavity in the joint.
The null hypothesis in this study is that cracking knuckles does not lead to any negative effects on the body. The alternative hypothesis is that cracking knuckles can lead to potential negative effects such as arthritis and other medical conditions.
So, the question being asked here is whether or not this cavity-popping habit actually harmful. Does the cracking of one’s knuckles (independent variable) cause arthritis (dependent variable) or any other medical conditions? Michael Behr, M.D. of Piedmont Healthcare doesn’t seem to think so. Although he does not directly dismiss the potential negative effects of knuckle cracking, he does say that there is no direct correlation between the cracking and arthritis or any other harmful medical condition. In addition, he makes it clear that although there is no proof that cracking leads to arthritis, any pain felt while cracking joints should be taken very seriously.
It is important to address and consider third variables when it comes to the development of medical conditions such as arthritis. Things like genetics play a big part in whether or not a person develops conditions, and even though a person who cracks their knuckles often may develop arthritis later in life, it can always be said that correlation does not equal causation. Elizabeth Cohen of CNN (2016) writes of a similar study as the one mentioned earlier in which joints were looked at before and after they were cracked under ultrasound. The study again showed that the knuckle crackers did not experience any negative effects, and were actually exposed to a greater range of motion. This topic does not suffer from the file drawer problem, as there has been more than one study put out on the matter. As of now, there are no active studies in progress on the topic.
To conclude, it can be said that as far as we know now, cracking your knuckles can actually be beneficial! The average person who cracks his or her knuckles should not stop doing so just because their parents asked them to.