He will miss the remainder of the season.
McAllister was hurt on a screen pass in the third quarter of the 52-3 setback at Lambeau Field. An MRI exam on Monday revealed the severity of the damage.
He had just 31 yards on 11 carries and caught three passes for an additional 33 yards before leaving the contest.
McAllister has run for 335 yards with three touchdowns this season and was the team's second-leading receiver with 17 catches for 117 yards.
Aaron Stecker and veteran Antowain Smith will have to fill the void in McAllister's absence.