The Baltimore Ravens placed starting middle linebacker Jameel McClain on injured reserve Saturday with a spinal cord contusion.
Ravens coach John Harbaugh announced that McClain would miss the remainder of the season on Monday.
McClain suffered the injury during a Week 14 game against the Washington Redskins.
The 27-year-old was held out of Sunday's loss to the Denver Broncos. He had started 45 consecutive contests for the Ravens and had never missed a game since joining the team as an undrafted free agent in 2008.
McClain had 79 tackles in 13 games this season.
To fill the roster spot, Baltimore signed linebacker Adrian Hamilton to the active roster from the practice squad.