Cracking knuckles can be addictive and studies show that as many as 54 percent of people crack their knuckles. What drives them to crack their knuckle with a “popping” sound? The synovial fluid in our joints serves a similar function as motor oil in a car’s engine, by lubricating our joints as well as reducing friction and preserving our cartilage. Synovial fluid contains various gases including oxygen, nitrogen, and carbon dioxide.
