The Bears have placed star linebacker Tremaine Edmunds on injured reserve with a groin issue, the team announced Saturday afternoon.

Running back Roschon Johnson (back) also was added to IR, so he and Edmunds will miss at least the next four games.

Linebacker Carl Jones Jr. and running back Brittain Brown were signed to the 53-man roster from the practice squad.

The prolonged loss of Edmunds is a significant blow to a Bears defense that has dealt with major injuries to key players most of the season. For example, the team will be without its three starting linebackers in Sunday’s game against the Pittsburgh Steelers. Linebacker T.J. Edwards has missed the past two games.

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Cornerback Jaylon Johnson and Kyler Gordon have been designated to return off IR reserve but, as expected, will remain on IR through the Steelers game. Johnson has practiced just four times since returning to on-field work from major surgery on his groin and core muscles. The Bears are being cautious with Gordon (groin/calf), who has dealt with soft-tissue injuries since training camp.

Edmunds was having an excellent season thus far, with 89 tackles, four interceptions, nine passes defensed and one sack. Defefensive coordinator Dennis Allen moved Edmunds to weakside linebacker, which has allowed him to use his athleticism and length well.

Rookie Ruben Hyppolite II will play in Edmunds’ stead.