I recently had surgery on my ankle and have started walking again. I find when I stretch or move it, it cracks and pops a lot more then it ever did before. This doesn’t cause pain, and sometimes even feels nice, but what makes the noise?
In: 4417
Bubbles popping.
Your joints are encased with a shock-absorbing fluid called synovial fluid. This stuff is non-newtonian – it’s liquid normally to lubricate your joints and reduce friction. But a sudden shock solidifies it to protect your joints.
Synovial fluid can get gas bubbles in it, and applying pressure pops these bubbles.
Surgery on a joint typically includes disrupting the synovial fluid in some way while also modifying the joint itself, leaving the fluid more susceptible to these bubbles until the joint heals.
To add on to what the other comment is saying, the gas that makes the “pop” is nitrogen, an inert gas that composes much of the atmosphere. The popping is when the gas escapes the joint, and no, there is nothing bad about popping your joints, and having joints that pop a lot don’t really mean anything.
[removed]
But where does the gas go? If the bubbles pop, doesn’t the stuff in the bubble go somewhere?
On that note, is it actually bad to crack your fingers all the time? It was a rumor growing up that it would give you arthritis.
Before I begin: not a doctor
I’ve seen several answers that say that these are bubbles popping in your joints. This was what was previously thought and is not the case anymore. [Recent MRI imaging](https://youtu.be/_ZNENkkf5Uw) has shown that this popping sound is actually the FORMATION of bubbles within your joint. This is why you get popping a lot more often with stretching, which leads to the formation of bubbles, than physical compressing activity, which would lead to the popping of the bubbles.
For example, when you pull on your fingers to pop them, you are creating a decrease in pressure due to an increase in volume of the cavity. This decrease in pressure allows bubbles of nitrogen and other gases to suddenly form and with that formation comes noise. After not moving for a while, the bubble naturally gets reabsorbed and you’re able to repeat the process and get another pop.
As for why it feels nice…no idea. Could be a perceived increase of flexibility due to no longer having to fight the potential of those gas bubbles forming since they’re already formed but that’s just a guess
Finger joint popping, back popping and most other “popping”, almost always synovial fluid. However, post surgical joints, aging knees, elbows and shoulders: might be crepitus. Crepitus is the grinding noise of bone/cartilage along rough areas or cartilage. It can be painful. In short: “pop” probably nitrogen bubbles in synovial fluid (not to be confused with “the bends”, “grinding” probably crepitus.
It (the popping noise) may actually be caused by the formation of the nitrogen gas, not the popping of the bubble:
“In 2015, research showed that bubbles remained in the fluid after cracking, suggesting that the cracking sound was produced when the bubble within the joint was formed, not when it collapsed. In 2018, a team in France created a mathematical simulation of what happens in a joint just before it cracks. The team concluded that the sound is caused by bubbles’ collapse, and bubbles observed in the fluid are the result of a partial collapse. Due to the theoretical basis and lack of physical experimentation, the scientific community is still not fully convinced of this conclusion.”
https://en.wikipedia.org/wiki/Cracking_joints?wprov=sfla1
Fluid moving through tight spaces. Similar to taking a ketchup packet and squishing the catsup back and forth. Synovial fluid is the ketsup and the knee capsule is the packet.
Holy cow. I am an orthopedist and the level of confidently incorrect in this thread is hurting my soul. The real answer is that it you can’t tell what is causing it without an exam. All of the right answers are here but you can’t tell which one it is. It is like saying you know why someone’s car isnt running well without looking at the car. BTW, the odds of this being synovial cavitation are nearly zero, much more likely some sort of soft tissue issue. You know that’s right because it rhymes.
Latest Answers