The belief is that Orton suffered the concussion when he delivered his RKO to the Big Show. After Orton delivers the move, he gets up very slowly and grabbing his head and is described as being on "spaghetti legs."
Backstage at RAW on Monday, nobody knew Orton was injured or at least they weren’t talking about it.
WWE.com ran an angle from this, which was also carried over to the SmackDown tapings. The angle claims that Orton suffered the concussion when Daniel Bryan hit him in the head with the World Title. We can't confirm that.