The Chiefs announced Tuesday they placed rookie safety Juan Thornhill on injured reserve.
Thornill tore an anterior cruciate ligament in Week 17 against the Chargers.
The second-round choice finished his rookie season with 58 tackles, three interceptions and a touchdown in 16 games.
The Chiefs filled his roster spot by promoting offensive guard Ryan Hunter from the practice squad.
Hunter appeared in three games for the Chiefs this season, playing 14 offensive snaps and 16 on special teams.
The Chiefs waived him Oct. 9 and re-signed him to the practice squad the following day.
Hunter went undrafted out of Bowling Green in 2018.