@notapizzaeater, I went to the pub after injuring my knee, hobbled up to the bar and got my round in and everything. I got a lift home from a colleague and when I tried to get out of the car my knee just gave way and I landed on my arse in the road.
I just thought it was a sprain, and used my (ex-nurse) mother's recommended treatment of a pad of cotton wool, soaked in witch hazel, and a crepe bandage, and took myself to bed. When I got up in the morning, I took the bandage off to see the damage and watched my knee swell up to the size of a cabbage.
I couldn't straighten it all, and took myself to hospital in a taxi. All morning, I lay on a couch with my knee slightly bent, as doctor after doctor rocked up and told me they were "just" going to try and straighten my knee. I repeatedly told them, in no uncertain terms, that they were doing no such thing unless I was unconscious. They agreed to knock me out, took me to theatre and I woke up with a full-length cast on it. No bugger could tell me wtf they'd done for ages.
I got the injury parachute jumping and the docs were intrigued as to where the hell I'd been parachuting in the vicinity of Balham (where the hospital was). When I explained I'd done it in Kent the day before, they were gobsmacked that I hadn't gone straight to hospital in an ambulance, and even more so when I told them I'd gathered up my parachute and walked for 15 minutes across fields (including climbing 2 stiles) to get back to the clubhouse.
I honestly don't remember it hurting much at the time. I had no idea I'd done proper damage.
They also told me to expect arthritis in it when I got older, but it's the other knee that's got the arthritis.