Montgomery suffered the injury on the third play of Sunday’s 22-20 victory over the Raiders.
The Bears signed Montgomery to a one-year contract in April because of his familiarity with head coach John Fox and offensive coordinator Adam Gase. Montgomery previously played under Fox in Carolina (2006) and Denver (2014).
The 32-year-old veteran has appeared in 110 games, with 75 career starts. Montgomery also played with the New York Jets (2007-08) and in Washington (2008-13).
On Sunday, the Bears replaced Montgomery at center with left guard Matt Slauson, who is a candidate to permanently take over the position. The Bears also invested a third-round draft pick this year in Oregon center Hroniss Grasu, but the rookie has been a healthy scratch in the first month of the season.
“I thought [Slauson] was tremendous,” Fox said. “That early in the game -- I think it as about the third play that Will went out -- it’s a two-man switch. Typically in this league, you go in with seven linemen, and even Patrick Omameh moving over to left guard and Matt going to center, it wasn’t all hunky-dory. But I thought they didn’t panic and just kept swinging the sword and did pretty well.”
The club’s new center will be tested Sunday when Chicago travels to Arrowhead Stadium to take on Kansas City.