The Seahawks placed Fant (knee) on injured reserve Wednesday, John Boyle of the team's official site reports.
Fant returned from injured reserve and played in Week 9 against the Rams, but he aggravated his knee injury during the game after playing just 17 offensive snaps. With Fant on IR again, he'll have to sit for at least the next four regular-season games. He is eligible to return from IR as early as Week 15 against the Packers on Sunday, Dec. 15.