Many people have mixed feelings about whether or not cracking knuckles is harmful. Knuckle cracking is common amongst many people; some do it out of habit while others find it quite annoying. What are the causes of the knuckle popping sound and can it be harmful?
Causes
According to Harvard Medical School, the “cracking” of knuckle cracking seems to be produced by increasing the space between finger joints. In the joint fluid, we get gas bubbles that collapse or burst. You aren’t able to crack the same knuckle or joint twice right away is that it takes some time for the gas bubbles to accumulate again in the joint.
Cracking the knuckles is probably harmless. Although there have been occasional reports of dislocations or tendon injuries from overly vigorous knuckle cracking, such problems seem very much to be the exception and not the rule.
Cavity formation
According to a study published by the journal PLoS One, a Canadian research team discussed how the bubble collapse can lead to cavity formation. The researchers collected real-time footage using magnetic resonance imaging (MRI) and concluded that joint cracking is related to cavity formation rather than the collapse of gas bubbles.
The scientists studied 10 metacarpophalangeal joints by inserting participants’ ‘ fingers into a tube that could be used to apply traction to the joint. They used the MRI to take images of what happened before and after the traction was applied to the point of cracking. The results showed the rapid creation of a cavity in the joint at the point of joint separation, and this produced the sound.
Tendons snapping over joints
Some doctors propose that the cracking sound made by joints is the result of tendons snapping into place over joints, says the health website Medical News Today. Joint cracking is often confused with the snapping sound made by stiff tendons or other bands of soft tissue sliding between muscles or over bony outcrops. Tendons keep muscles attached to bones, while ligaments connect bones to other bones.
Doctors believe that tendons can make a popping noise when they quickly snap over a joint. Ligaments may make popping noises when they tighten while the joint is moving. When a joint move, the tendon changes position relative to the joint. After the tendon changes position, there may be a sudden snap as it returns to its original location. These noises are often heard in the knee and ankle joints when standing up from a seated position or when walking up or down the stairs.
Is it damaging?
According to the health website VerywellHealth, one study was found that there was no increase of hand arthritis among knuckle crackers. However, knuckle cracking may be correlated to hand swelling and lower grip strength.
Sources:
https://www.health.harvard.edu/blog/knuckle-cracking-annoying-and-harmful-or-just-annoying-2018051413797
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0119470
https://www.medicalnewstoday.com/articles/259603.php
https://www.verywellhealth.com/does-cracking-your-knuckles-cause-arthritis-2552115
