Indianapolis Colts defensive tackle has a dislocated right ankle and will have surgery that will likely end his season.
Foster had his right foot entangled in a pile following a play at the end of the first half. He remained on the ground and had an air cast placed on his leg before being carted off the field.
Foster entered the game with 12 tackles this season, his fourth in the NFL.
The winless Colts have injury issues on the offensive line as well as rookie left tackle Anthony Castonzo was on crutches after Monday's loss at Tampa Bay with his left ankle in a walking boot.
Castonzo was the 22nd overall pick in the 2011 draft.