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Comment by Crito | Hacker News Reader

My ankle does the exact same. My understanding is that for this sort of cracking, where there is no "refractory period" between cracks, the gas bubble thing is not the cause. Rather it might be a tendon "snapping" across a bone, like some sort of bistable system.

I also have another sort of cracking where the refractory period is weeks, rather than ~20 minutes. I suspect this is another phenomenon as well, though I don't know what it might be. I experience this in my wrists, sometimes sternum (perhaps snapping cartilage in the xiphoid process? I really try to avoid this one.)

My elbows also crack when I hyperextend them. The refractory period there is probably somewhere between 20 minutes and an hour, but I'm not convinced that is the gas bubble thing either.

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I pop my knuckles, all 3 thumb joints, wrists (by pronation of hand and supination of forearms, or vice versa), elbows (by hyperextension), shoulders, and cervical vertebrae on a regular basis, and occasionally thoracic vertebrae, toes, and hips. I can very rarely manage to pop one knee or the other, or lumbar vertebrae. I have never been able to pop anything in my ankle; there's just too much joint stabilization there. But I can manage the metatarsal-cuboid joints sometimes by twisting the foot from the toes.

If you can snap your ankle every time you move it in a particular way, it is probably not the same thing. I have never been able to pop the same joint twice in rapid succession. Indeed, that's why I pop so many different joints. Once you've done them all, there's no choice but to wait.

I'd certainly be wary of pops emanating from joints without a great deal of natural range of motion, or those so wrapped up in muscles and ligaments it is practically impossible to isolate any one joint in particular. If you experience any pain while joint-popping, stop doing it, immediately.

Wow, how did you manage to do the thoracic vertebrae? I have been trying to achieve that one for years! On the plus side, I was able to master repeated ankle cracking without refractory period - So I haven't exactly wasted my life.

There are two reliable ways to do it. First, you cross your arms over your chest and put your hands on the opposite shoulders. A brawny accomplice then stands behind you and picks you up by your elbows. Your spine is stretched by your own body weight and your accomplice's chest. That is truly satisfying, but I haven't had it done in many years.

Second method, you put your back against a hard, flat surface and push yourself into it. This one may only pop one or two at a time. And you might break your furniture.

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