Don't be so obsessed with the knee, it's clearly just a premise born from a meme. Dude's OP as shit, his knee's probably just a minor annoyance and he's using it as an excuse to live a peaceful life.
@Varler Ever seen someone spit out a tooth after a really hard blow to the face? Yeah, that wolf got beaten white and blue by the MC, so it's no surprise that one of its tooth got "a bit loose".