Coach Ben Johnson said the Bears will place Sewell (Achilles) on injured reserve Wednesday, Courtney Cronin of ESPN.com reports.
Sewell suffered a torn Achilles in Sunday night's loss to the 49ers and will miss Week 18 and the playoffs for Chicago. Sewell served as the Bears' top reserve linebacker and a top special-teamer. He appeared in 13 games, making nine starts, and recorded a career-high 59 tackles (33 solo) and one forced fumble.