An MRI on Monday revealed more damage than initially believed with Burrow tearing his ACL and MCL in addition to other structural issues in his left knee.
The Bengals moved Burrow to injured reserve Monday afternoon.
“The injury will require surgery and rehabilitation, though the team’s medical professionals expect him to fully recover and be back to lead the team next season,” the team said in a statement announcing the move.
Burrow started 10 games and completed 264 of 404 passes for 2,688 yards with 13 touchdowns and five interceptions. He rushed 37 times for 142 yards and three touchdowns.
The Bengals signed quarterback Brandon Allen off the practice squad. They also have Ryan Finley on the active roster at the position.
Allen entered the league as a sixth-round choice of the Jaguars in 2016. He later spent time with the Rams and Broncos.
Allen spent the first 10 games of this season on Cincinnati’s practice squad after joining the team as a free agent Aug. 1.
He has played three career games — all with Denver in 2019 — and has completed 39 of 84 passes for 515 yards with three touchdowns and two interceptions.
The Bengals also signed offensive guard Quinton Spain off the practice squad. He joined the Bengals’ practice squad Oct. 30, and as a game-day call-up, he has played all three games with two starts for Cincinnati since.