(CBS) The Chicago Bears have placed defensive lineman Ego Ferguson on the injured reserve list, the team announced Saturday.

Ferguson had been dealing with a knee injury lately and most recently was tabbed as doubtful for Sunday’s game after not practicing Thursday and Friday. Now, his season is done.

Ferguson has appeared in 20 games and started one in two seasons with the Bears, recording 36 tackles and two sacks. The Bears selected Ferguson in the second round of the 2014 NFL Draft.

In a corresponding move, the Bears signed defensive lineman Bruce Gaston, who appeared in two games this season with the Green Bay Packers. Gaston entered the NFL as an undrafted free agent in 2014 and is a Chicago native, graduating from St. Rita High School.