Source: Josh Alper, NBC Sports Pro Football Talk 
Bears quarterback Jay Cutler left Sunday’s loss to the Lions before the team’s final drive because of an ankle injury, not an aggravation of the groin injury that kept him out of the lineup last week.
After the game, Cutler said, via Adam Jahns of the Chicago Sun-Times, that he rolled his left ankle during the first half of the game and that limited his mobility in the second half before he finally came out of the game. It was clear watching Cutler that he was operating at less than full speed, though he said it was just his ankle bothering him and that his groin was fine. That lack of mobility wound up leading to the decision to remove Cutler from the game.
#Bears  QB Jay Cutler said his offensive line knew he wasn’t going to be as mobile and that his injured ankle made him “more restricted.”
— Adam Jahns (@adamjahns) November 10, 2013