Popular wisdom has insisted that, by cracking your knuckles, you will inevitably develop arthritis in later years. According to Dr. Jack Choueka, Chair of Orthopedic Surgery at Maimonides Medical Center, however, that is simply not the case. "A healthy joint is surrounded by fluid containing oxygen, nitrogen and carbon dioxide gasses," explains Dr. Choueka. "The 'cracking' that you hear when cracking your knuckles is a result of gas bubbles popping within the fluid of your joints. The belief that this action increases one's risk of arthritis is not supported by any evidence." After the gas bubbles pop, it takes time (anywhere from a few seconds to a few minutes) for them to re-form, which explains why it's rare to be able to crack your knuckles twice in immediate succession.