Chicago Bears wide receiver Johnny Knox told reporters on Wednesday that he's done with football thanks to a vicious back injury that required spinal surgery. Troup, a 2010 second-round draft pick that has thus far only appeared in 21 games, landed on IR with the back injury in 2011, had off-season surgery, and then couldn't make it through camp practices healthy last summer before the team shut him down for the year again in mid-August. recently caught up with Troup on his road back to the lineup, but clearly, the 315-pound defensive tackle still has the injury on his mind.