The Truth Behind Cracking Your Knuckles

The popping or cracking sounds heard when you bend your finger joints may not be what you think. For years those that cracked their knuckles, pulled out their toes, twisted and popped their neck or back may have been told to stop or suffer future arthritic effects. Not to mention the sheer horror of a sound that mimics bones being splintered which makes most people wince.

Recently, scientists looked into knuckle cracking with new technology that could actually video in real time what exactly happens when a bone is bent or pulled into a loud snap. The results were surprising to some and, to others, confirmed many theories presented over the years.

Daily Crackers

For some, cracking their knuckles could be a nervous habit while others gain a profound sense of relief. Either way, according to a study published in the Journal of the American Board of Family Medicine (JABFM), approximately 25%-54% of people crack their knuckles daily with men more prone to rattle their joints than women. Some report immediately relief gaining more range of motion (ROM) and less tension in the joint.

Yet, there are also those that feel cracking knuckles or popping vertebrae is akin to potential damage.

A One Man Study

Before the advent of more advanced medical technology one doctor took knuckle cracking into his own hands, literally. Medical doctor Donald Unger took it upon himself to create his very own one man study of knuckle cracking. He purposely cracked the knuckles on his left hand every day, twice a day for over a fifty-year period while never cracking his right hand.

His results showed that, contrary to family members continually telling him he was creating a dangerous future for his joints, both hands remained unaffected. No arthritis or other joint afflictions ensued prompting Dr. Unger to unofficially determine that knuckle cracking is safe. In fact, in 2009, he was awarded with the Ig Nobel Prize, a parody of the actual Nobel Prize but one that is sometimes described as an award that at first makes you laugh and then makes you think.

A Crack Investigation

Since Dr. Unger’s self-proclaimed one man clinical study, other researchers have stepped up to look closer at what happens when a knuckle is cracked. It turns out that there is an inter-joint process that occurs which answers the age-old popping question.

A 2015 study published in the journal PLoS One lead by researchers at the University of Alberta inspected joint pulling under magnetic resonance imaging (MRI) slowed down to less than 310 milliseconds.

Medical News Today (MNT) describes the joint popping process viewed under MRI scans,

“When a finger or joint is extended, the pressure inside the finger is lowered and the gases that are present, such as carbon dioxide, are released in the form of a bubble. This action creates a vacuum that the gases then fill. As the pressure of the synovial fluid drops, gasses dissolved in the fluid become less soluble, forming bubbles.When joints are extended through pulling, there is a sudden and dramatic increase in surrounding pressure that causes a corresponding sudden partial or total collapse of these gas bubbles. This rapid implosion, collapse, or bursting of the gas bubbles creates an audible popping sound. The bubbles pop when the bones are pulled apart, creating negative pressure.”

May Be Ok, May Not Be Ok

Most medical practitioners will tell you that it’s probably not a good idea to habitually crack your knuckles, but that that it probably won’t harm you. In the JABFM study, it was concluded that,

“…in these cohorts of persons aged 50 to 89 years, a history of habitual KC [knuckle cracking] – including the total duration and total cumulative exposure to KC – does not seem to be a risk factor for hand OA [osteoarthritis].”

However, like anything done to excess, there is always a chance for some to have less resilience than others. If you do not develop arthritis from accumulated knuckle cracking, there is a chance this habit may cause inflammation and weaken your grip.

MNT cites the results from a 1990 study by researchers at the Department of Internal Medicine, Mount Carmel Mercy Hospital, in Detroit, Michigan which showed the potential for joint damage in some knuckle crackers,

“…focused on 300 participants over the age of 45, 74 of whom cracked their knuckles, 226 did not. Both groups showed similar rates of arthritis in their hands. However, the 74 who cracked their joints showed a higher rate of inflammation of the hands and a weaker grip. So, while joint cracking may not cause arthritis, it can have a negative impact on the overall health and strength of hands.”

Crack your knuckles if you like but there’s no guarantee you won’t end up a claw handed cripple. It’s probably best to keep your cracking to a minimum, not necessarily for your sake but for the sanity of those around you.