Anecdota

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Why Do Knuckles Crack? – A UC Davis Health Study


We studied knuckle cracking because it is a very common and controversial topic In particular, 25-50% of people identify themselves as knuckle crackers at some point in their lives People come in all the time asking wither knuckle cracking is going to cause arthritis But, they keep doing it because it give them a feeling of relief from tension Our study was the first one that synced up what we heard and what we saw at the same time So, we were using real time ultra-sound to look at the joint as it popped And what we found was something that looked to us like the fourth of July A tiny firework explosion in the joint that occured everytime Very distinctive, very unusal, we know that this appearance is caused by gas Or bubbles forming at the joint We found consistently that the sound came before the flash that we see of the bubble coming into the joint So, there is dissolved gas in the joint fluid that gets liberated And it’s actually that bubble formation that is assoicated with the pop not the bubble popping like a balloon There was a recent study out of Canada earlier this that got a lot of press It looked at one person, cracking his knuckles in a MRI scanner Now, MRI is not as fast and can’t see things as small as ultrasound But in that study, they actually were able to visualize in that one individual the process of knuckle cracking So that was very interesting But, we were able to do is look at knuckle cracking much more quickly Look at much more detail and also to listen to the sound of the crack at the same time as watching the joint Which, they were not able to do with MRI We have an intense interest in musculoskeletal imaging and caring for patients with orthpedic issues So we really wanted to know for our patients wither it was causing any problems or not to be knuckle cracking We really are well positioned here at UC Davis to have multidisciplinary team So we’ve got the hand specialists, the orthopedics We’ve got the diagnosing imaging specialists and we’ve got the great equipment We looked at 400 knuckles… In a very detailed way Asking people about any problems with their knuckles or their extremities We asked about any symptoms of weakness or swelling or any problems with their hands in general What we’d like to do now is expand it, to look at thousands of people with a survey world wide One piece of advice is that people sometimes don’t like their co-workers and family members to knuckle crack So that’s been an interesting re-occuring story that we have heard… However, we have not found any short term adverse effects of knuckle cracking So maybe irritating to others but not to the joints that are being cracked

One thought on “Why Do Knuckles Crack? – A UC Davis Health Study

  1. When you pop your knuckles you're basically doing the same thing that a chiropractor does when he pops your back. It's funny how knuckle popping has such a bad rap when chiropractic "adjustments" are considered beneficial

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