It is good to know that my old body can still take a bit of abuse.
While cleaning my floors today, I jumped over a wet spot -- and caught the edge of a rug, which moved and sent me on the way toward being head-over-heels. My right leg went all twisty in the sort of way it shouldn't, and there was a moment of panic -- the feeling of losing complete control. I suppose this doesn't happen very often when you're an adult. I only remember moments like that when I was a kid, or playing sports as a teenager (nearly every tackle in football was a short burst of trauma), or the car wreck (not my fault) I had fifteen years ago.
But after a few minutes of wondering if I had done something bad to my knee, all seems well. And the floors are clean.