The Bills elevated Klein to the active roster Saturday.

Klein (back) was a full participant in Friday's practice.

Klein (back) was a limited participant in Thursday's practice.

Klein (back) has been ruled out ahead of Sunday's game against the Bengals, Alaina Getzenberg of ESPN.com reports.

Klein suffered a back injury Wednesday and will not practice Thursday, Chris Brown of the Bills' official site reports.

The Bills signed Klein to their active roster Wednesday, Maddy Glab of the team's official site reports.

Klein was signed to the practice squad Thursday, Alec White of the Bills' official site reports.

The Bills signed Klein to a one-year contract Monday, Grace Heidinger of the team's official site reports.

The Bills claimed Klein off waivers from the Bears on Thursday.

Baltimore traded Klein along with second and fifth-round draft picks to the Bears in exchange for Roquan Smith on Monday, Josina Anderson of CBS Sports reports.