Can insurance deny you coverage for an old untreated injury?

Basically, when I was 24 I had a bike accident. It was the dummest thing, where I was parked and didn’t notice the front wheel had ridden on top of a log, so when I sat down the bike moved, I accelerated by mistake and ended up being thrown off the bike. I landed squarely on my knees.

Like, I said, I was more embarrassed that it happened than anything else, and quickly got up and moved out of the way for other people. Got home, took a shower and that’s when I realized my knees where starting to swell. They ballooned to almost twice their size, but, I was stupid and didn’t go to a doctor. I just did the RICE method and after about two weeks the bruising and swelling went away. I put the whole thing out of my mind and moved on.

I’m 38 now, and a couple of years ago I started having issues at the gym when I tried to put pressure directly on my knees. Basically, I’m at the point where if I want to get on my knees, I need to have a mat that’s at least 1.5 inches thick. If I get on all four directly on the floor, within seconds my knees explode in pain. My left knees has also started to click loudly when I bent it.

I don’t know if this is directly a result of the bike accident, though, I don’t see what else it could be. I’m a healthy person in general. My question is, when I go to the doctor and he asks why I think this is happening, should I mention the bike accident and risk having insurance coverage denied, or should I not even mention it to be on the safe side?