I can’t remember what I did to it, but my right knee was aching slightly when I got up from kneeling for a few weeks. I knelt down and it cracked just about 20 minutes ago, now the ache is gone completely. What just happened?
I’d think that the Perfect Master’s offhand comment about some cracking being of a ligament snapping over a bony projection might be more relevant than most of the column, which is about knuckle cracking.
This is unrelated to the sort of joint popping and ligament snapping referenced by Cecil in his column on cracking knuckles.
It’s much more likely that your knee cushioning cartilage–the meniscus–(probably medial; possibly lateral) is partially torn, or at least has a little degeneration. This can produce a little mild chronic ache or severe pain, depending on the nature of the problem. Shifting position can cause some noise when a bit of abnormal cartilage is trapped and then shifts…it’s even possible for a small segment to be dislodged and cause a loose body in the knee. Various manipulations and changes of position can relieve or exacerbate discomfort depending what is getting shifted where. The noise in this case has nothing to do with joint fluid expanding into a gas, and probably nothing to do with ligaments sliding around either. There are a couple of crossed stabilizing ligaments in the knee (the cruciates) and some stabilizing ligaments on each side (medial and lateral collaterals) but I would be less suspicious of these causing your particular observations.
This is not a diagnosis, of course. For all I know you have cancer of the bone and that’s causing your symptoms. But it’s a much more likely cause of what’s going on.