How many times growing up were you told not to crack your knuckles because it causes arthritis? That is not correct. Studies have shown that people who crack their knuckles statistically have less arthritis than those that don’t. Chances are your mom told you that because the sound was driving her crazy, or because that is what her mother told her. Like most wives’ tales it is a myth that has no legs to stand on.
New research demonstrates what really happens when you crack your knuckles, and I now know that I have been a little wrong on how I’ve been explaining it for the past 30 years. New MRI motion studies of knuckle cracking demonstrate what really happens. All joints are totally encased in a fibrous sac called a joint capsule. Inside the joint capsule is synovial fluid which is a viscus, non-Newtonian liquid which functions to lubricate and reduce friction between the articular cartilage to reduce friction during joint motion. When a joint, is elongated, and it’s volume is expanded, a gas bubble forms. The “cracking” sound occurs the instant that the bubble forms, suggesting that the sound is caused by the gas bubble inflating. For years the accepted wisdom was that the crack happened when the gas bubble either popped or collapsed.
It’s good to know what is really happening in the body. Even more important, it is important to know that knuckle cracking is not bad for you. Cracking your neck and back is a whole different issue. The same phenomenon happens, but the environment is much more complicated. There are 24 vertebrae in the spine and up to 135 joints. The facet joints (or back joints) are very close to the spinal nerves. People who are always cracking their spines are probably moving areas of the spine that are hypermobile which are compensating for areas of the spine that are hypomobile, or stuck. Constantly moving these facet joints can irritate the spinal nerves as they exit your spine causing a plethora of pain and functional problems
So go ahead and crack your knuckles to your hearts content, but please leave the back cracking to your chiropractor, who is an expert in manipulation.
To watch the video (which unfortunately has no sound) or tor read more detail about the experiment, click the following link: http://www.npr.org/blogs/health/2015/04/15/399636388/why-knuckles-crack