Some are claiming that Silva's injury was a freak injury. In truth, the snapping of the shin bone in that manner was a rare injury, but when a fighter runs full power into a kick which connects on the opponent's knee, it's not uncommon.
Within that scenario, it is a very common outcome that the shin will be injured to some degree. Whether the fighter can fight on it or not, he will not want to kick again too soon, and that is the purpose of checking with the top of the shin and knee.
No, freak injury implies it was simply misfortune. There was nothing accidental about Silva getting hurt. When a hard kicker kicks a knee, he hurts himself. Sometimes it's enough to finish a fight, sometimes it's just enough to stop him from kicking for a while, but kick a knee Silva did.