Guys are stubborn that way. Must be the same issue that makes them not want to ask for directions... If he complains about the discomfort, tell him there's a solution - GO TO THE DOCTOR. And tell him you don't want to hear his complaints if he's not going to even bother doing anything to solve the problem. Appeal to his reason. Explain that his injuries aren't going to get any better the way they are and they could be serious; does he still want to be in pain a year from now?

I'm afraid I'm of the "get it looked at or shut the f**k up" school of thought. I just do not get this aspect of the male persona, I've known so many of them with exactly the same attitude and it's just plain annoying! I'm more than willing to sympathise with anyone who has hurt themselves, but when they won't do anything about it, please....

Tell him that if he doesn't get his knee looked at, he will probably be in a wheelchair this time next year - and forever unless he goes abroad for a knee replacement.