I just realized something. House's leg problem is two fold. 1 - the constant pain. 2 - he lost a big chunk of muscle. The constant pain is why he's on Vicodin. But even if he weren't in pain at all, he'd still have to deal with the loss of functionality - he'd still be disabled. The pain makes it much, much worse, but even if it didn't hurt,he wouldn't be able to dance on stairs and he'd still need his cane to get across a room.
He's so focused on his pain that he forgot that.
And so did I, during the course of this episode.
I hope the writers didn't.