Washington (knee) was placed on injured reserve Friday, Katherine Terrell of ESPN.com reports.
Washington missed the Week 11 game against Baltimore and has been unable to practice the last two weeks. The Bengals signed Christian Ringo to bolster their defensive line depth, as they currently have four players from the group on IR.
Washington (knee) will not play Sunday against the Ravens, Paul Dehner Jr. of the Cincinnati Enquirer reports.
Washington was unable to practice in any capacity this week. After missing four of his first six games, Washington put together a stretch of three healthy games -- he logged five tackles (two solo) over 85 defensive snaps in those games.
Washington agreed to join Dallas' practice squad Tuesday, Brandon George of The Dallas Morning News reports.
Washington was waived by the Bills on Sept. 10 after appearing in 32 games for the club. A 2016 third-round pick, Washington takes the spot vacated by Aziz Shittu, who was released from the practice squad Tuesday. He has 3.5 sacks in his NFL career.