Bolles will undergo an MRI and other exams Friday morning to see if he will need surgery to repair the injury and determine how much time he might miss.
"Garett, obviously, did not look very good there," Broncos coach Nathaniel Hackett said. "So we'll evaluate there a little more. We've got to get in there and see him."
There was some concern among team officials afterward that Bolles could miss at least two months in the best-case scenario. A sixth-year veteran, Bolles has been one of the team's most durable players, starting from his first game as a rookie in 2016 and missing just four games in his career.
Three of those missed games came last season, including two with an ankle injury and another on the COVID-19 reserve list.
Bolles was injured on a first-and-15 play from the Colts' 42-yard line with 3 minutes, 58 seconds left to play in regulation. Broncos running back Mike Boone ran off left tackle for 3 yards, and a Colts player appeared to roll on to Bolles' leg.
Bolles stayed down on the field after the play and was then taken to the locker room on a cart after he had been checked by the Broncos' medical staff.
Bolles' injury was the most serious among a long list for the Broncos on Thursday night. Linebacker Josey Jewell and cornerback Ronald Darby both left with knee injuries that will be evaluated Monday. Outside linebacker Baron Browning didn't finish the game because of a wrist injury.
Those injuries came just four days after running back Javonte Williams suffered a season-ending knee injury in Sunday's loss to the Las Vegas Raiders and outside linebacker Randy Gregory suffered a meniscus injury that will force him to miss several weeks.