Der! Probably! Popping your knuckles doesn't technically cause any damage to the joint but could over-stretch the muscles and ligaments. So stop doing it! If you sat next to me at work I probably would have caused you even more damage by now! Oh dear - don't mean to be mean... it's just that it goes right through me when someone does that - like fingernails down a blackboard. Take some ibuprofen or asprin to reduce the swelling you've probably caused, and put some ice on it.