Damn dude my aunt and mom both had knee issues like that, they had no cartilage (or whatever it is that absorbs the impacts there... I think it's the cartilage) and were always bone-on-bone, and apparently it's excruciating. They have shots that inject some padding in there but it will wear down, etc. My aunt has it far worse (I think she has none left, my mom has little), she can barely walk. It's pretty sad
She's also going blind, not sure what it is but basically the center of vision will eventually go away (she'll only be able to see in her peripheral, not sure if that will be affected or by how much).
But yeah ruining your knees/ankles would be pretty terrible, it's a good reason to go easy on running, and to learn how to run properly. You're supposed to run on the balls of your feet, etc. etc. Though isn't biking still hard on parts, like your hips and lower back? You're also more susceptible to hemorrhoids, aren't you? I like biking/cycling more (I don't actually own a bike, I use a stationary one) than running for sure.
I've still got cartilage, what they've got is worse tho I'm still susceptible. yeah, biking has its own set of issues depending on the type of bike you ride. guys can get temporary prostate problems from the seat too
and yeah my problem appeared because I wasn't running/walking properly and my arches were falling. I'm sure you can run a moderate amount without anything bad happening