Garett Bolles has added to the Denver Broncos' offensive injury woes, suffering a broken leg in the 12-9 overtime defeat to the Indianapolis Colts.

The sixth-year left tackle was forced off with just under four minutes remaining of the fourth quarter on Thursday and was seen on crutches after the game.

Initial tests revealed a broken leg, but the team were awaiting further evaluation on Friday and it was then confirmed by head coach Nathaniel Hackett that he would be out for the remainder of the season.

"Garett Bolles will need surgery. He'll be out for the season." he said.

The Broncos' offense had already lost starting running back Javonte Williams to a season-ending knee injury in a Week 4 defeat to the Las Vegas Raiders, with the injuries coming amid on-field woes for the side.

Cornerback Ronald Darby has also been ruled out for the season after suffering an ACL injury and Hackett confirmed he is set for surgery.

Defeat to the Colts left the Broncos 2-3 for the season and are they yet to find their feet under Russell Wilson, following his seismic trade from the Seattle Seahawks.

The Broncos have plenty of time to improve before they take to the field in Week 6 against division rivals the Los Angeles Chargers, the game coming on Monday October 18.