text: what exactly makes the "cracking" noise when you crack your knuckles.?   when you crack your knuckles, your are moving the cartilage are getting air between the joints which make the 'cracking' noise. studies show that the more your crack your knuckles, the more prone you will be to arthritis when you become older. cracking your knuckles may feel good, but it decreases and weakens the cartilage in the joints.