The Cleveland Browns placed safety Usama Young on injured reserve and signed free-agent quarterback Josh Johnson on Wedneday.
The Browns also signed defensive back Jordan Mabin to the practice squad.
Young's thumb injury, which happened in the Browns' loss to Denver last Sunday, likely will require surgery, the team said. The sixth-year pro played in 13 games and started 11 this year, logging 52 tackles, 1.5 sacks, three interceptions, seven passes defensed and a fumble recovery.
Johnson, a fifth-round draft choice by Tampa Bay in 2008, will add depth at quarterback. He signed with San Francisco in 2012 but was released on Aug. 31. He has played in 26 games for the Buccaneers during his career and passed for 1,042 yards with five touchdowns and 10 interceptions.
Mabin, an undrafted rookie free agent, spent two weeks on the Baltimore Ravens' practice squad this season.