There is no way a player with an already broken leg could have played an entire game like Cesc Fabregas did against Barca.
He broke it in the Carlos Puyol tackle and his heroics stand but to speculate that he was sent to the pitch because the Arsenal medical staff were trying to hoodwink Wenger into believing his fitness is quite irresponsible.
This is not to say that preceding injuries have no part to play in his cracked fibula- injuries accumulate and with Craig Gardner's mistimed tackle and Puyol's collision occurring on the same area of the leg, and/or the impact of the penalty (he really whacked the ball), all could have contributed to the fracture. A very unfortunate sequence of events indeed.
Wenger on Cesc's injury:
"We have two independent doctors with x-rays who clarified that situation, that the bone was perfectly okay -- a bruised bone, but not broken before the game."
It would be a reversal of roles with Wenger usually quick to condemn national coaches for exposing players to injury. But Spain is also surely watching with some degree of anxiety and the blame game can go both ways. I don't think Arsenal with its stable of international players, many who are going to the World Cup are willing to risk their reputation.