Why do your knuckles pop?

You may be a knuckle-cracker or you may hate people doing it (it’s a bit like Marmite I guess, you either love it or hate it) but why do knuckles pop? In fact we could ask the same question about most joints in our body. Joint “self-cracking” brings relief to some people while it’s just a habit for others. The most common joints to self-crack are those in the fingers. There are different theories why it may happen and the video below (worth watching – quite fun) explains some of them. The noise is not always due to the joint: sometimes it’s due to a tendon snapping over a bone.

Dr Unger, a very interesting medical doctor and probably a slightly stubborn one, cracked the knuckles of one of his hands for 50 years (approximately 36500 times) and did not crack the knuckles of his other hand to use it as a control. He found no difference between his hands. He published a letter in the leading journal in rheumatology. While it provides a low level of evidence, it’s nevertheless interesting to know if you are a knuckle cracker: next time you hear someone telling you that you’ll get arthritis if you keep doing it, you can tell them about Dr Unger’s experiment.