In reply to The sharp end:
My knee is shot.
I had a bucket handle tear which eventually resulted in a 90 degree locked knee. I had no pain or swelling leading upto the locking up, but was aware something wasn't right, when it happened i just couldn't straighten my knee at all. Heroically down climbed the v6 I was on. Hospital, surgery, and a reasonable, amount of tissue removed. I then had pain and swelling, which subsided slowly.
I then made the decision to stop bouldering as I figured the impact would not help it in the long term. Falling on ropes only.
It took 6 months to get back to the standard I was at before the surgery, and longer to regain full confidence in my knee.
I now struggle with heavy packs and walking down hill. I'd recommend walking poles to assist if this becomes a problem.
Runing I think is a silly idea, and my knee complains within 100 yds of doing so. Cycling is a better low impact option.
I have a friend who has had both knees chopped the same, and he does iron mans for fun these days. I think you get a different genie each time the lamp is rubbed.
I expect a knee replacement at some point in the future. I've waited 5 years and taken out private medical insurance, the NHS isn't always the best for non life threatening injury and my lively hood relies on a level of physical ability.
Good luck, you've got the hand you've been dealt, and you can't change that. You just have to adapt and use your bonce.