LAKE FOREST, Ill. (CBS) – Bears safety Chris Conte was placed on injured reserved along with wide receiver Johnny Knox, who had back surgery Monday, the team announced in a news release.

Conte’s injury is a foot and ankle sprain.

Knox was second in the NFL in receiving average in 2011 at 19.6 yards per catch, with a team-high 727 receiving yards on 37 receptions with two touchdowns.

Conte had started the last nine contests at free safety in his rookie season, recording 47 tackles and one interception.

Meanwhile, the Bears announced additions to the 53-man roster. Signed from the practice squad were runningback Armando Allen, defensive end Thaddeus Gibson and wide receiver Max Komar. Runningback Robert Hughes joins  the practice squad.

Allen, Gibson and Komar are signed through the 2013 season.

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