It doesn't have to be a broken limb, that's just an example of the most extreme injury you'd typically see in non-motorized sports. It could be any serious injury. Regarding Jack99's comment, I'm not talking about a hairline fracture that can be ignored with enough adrenaline. I mean a serious fracture. They don't walk it off, they get carted away on a stretcher. I would equate this to "dying" D&D. You cannot walk off something that serious because someone tells you to. You cannot reconcile the dying condition with fatigue, or being out of luck points, poor morale or hurt feelings, etc (which all supposedly represent hit points in 4E. It seems as if an enemy sneezes in your direction, you take damage). It's not called "not wanting to fight" or even "not able to fight". It's called "dying". If they want PC's to never be dying, but just not able to fight, they really need to rethink the terminology. But then again, without the threat of death, it's not that heroic a game anymore. Who cares if you made a heroic stand against the dragon, if it never has even the slightest chance of killing you?