I'm fortunate never to have had a serious knee injury.
OF course, by now I've adapted my game so I rarely drive anymore and don't try to make overly athletic plays. I remember when I was young(er) and a big oldhead would show up, and invariably they'd have some sort of knee brace on.
I had a weird incident 2 months ago, where I overdid it the week before Chinese New Year, knowing I'd have two weeks off. (I played 4 hours Tues night and then both TH and FRI for two each). Woke up Saturday around 3:AM and my knee hurt as though sleeping on my side had pushed it out of joint/alignment somehow. So I got up, limped out into the garden, and fed all the outdoor cats (5). Was able to go up and down a ladder-- most are roof cats above the back and side walls. But was limpy with discomfort. Came back in and the knee felt like it'd pop with a few gentle swings. Being tired I thought it'd pop back into place, like I do with my elbow now and then when carrying groceries and it gets awkwardly out of joint/painful feeling. And I often pop the knee with a few gentle sitting leg bends.
This time, it got ready to pop, then did some bizarre triple pop. Felt like first behind the knee, then the cap, and then deep in the middle, with a weird feeling of pseudo-pain between pops. Afterwards, the alignment felt better/right but then my knee felt a bit unstable. And the next few days when I'd bend it I'd hear gravelly crunching inside. And I thought I might be farked. But after two weeks, I played my usual Tuesday night game, moving a bit carefully. No problem. And after a week or two of playing, it seemed fairly stable and almost normal.
I've kind of forgotten about it now. Not sure what I did, but at least one of those pops led to some loose material floating about internally. Cartilage? Meniscus tear? It turned out to be minor enough and short-term that I didn't even ask my doctor friends what might have happened in my knee. Well, they are brain surgeons anyway, but pretty sharp fellas. Have to say I was a bit worried about the prospect of having to retire form hoops.