Injuries going into UFC 117, UFC 118

Not a good day for injuries it seems, with 2 fighters pulling out from 2 different UFC's.  First, Thiago Silva has pulled out of UFC 117, likely due to a back injury he would rather not disclose.  It has been officially confirmed that Todd Brown will replace him in the fight.  Second, Phil Baroni has pulled out of his fight at UFC 118 due to a minor collarbone injury.  Very disappointed he pulled out of such an important card, with what sounds to be such a recoverable injury.