Linebacker Danny Trevathan was taken to the locker room late in the first quarter with the Bears trailing the Detroit Lions 3-0 with what appears to be a serious left arm/elbow injury.

Trevathan, a Pro Bowl alternate last season who leads the Bears with 67 tackles, suffered the injury on a narrow missed sack when he landed awkwardly on the arm and it appeared to twist backward. He immediately took himself out of the game and headed to the medical tent on the sideline before walking to the locker room with a member of the Bears medical team.

The Bears are already missing one of their other defensive leaders, Akiem Hicks, who was placed on injured reserve in Week 5 after dislocating his left elbow. They've struggled mightily to overcome his absence, and with 2018 first-rounder Roquan Smith dealing with his own on-field regression, playing without Trevathan — a free agent at the end of the year — for any extended period would be be extremely difficult.

Bears Insider will update this breaking story as more details become available.