By Chris Emma–

(CBS) The Bears have lost their key depth on the offensive line, with interior lineman Eric Kush having been placed on injured reserve with a torn hamstring, as coach John Fox announced Monday after practice.

Kush will have surgery Tuesday, and his season is now officially over. The Bears have signed undrafted rookie offensive lineman Brandon Greene to the roster to take Kush’s place.

An Alabama product, Greene played a number of roles with the Crimson Tide, most recently serving as a primary blocker at tight end. The Bears list him at 6-foot-5 and 295 pounds.

Kush played eight games and made four starts last season, proving to be an important piece after the Bears lost guards Kyle Long and Josh Sitton to injuries.

With Kush now sidelined, the Bears worked center Cody Whitehair in at guard for reps while Hroniss Grasu saw time at center. The team continues to ease Long back from his offseason ankle procedure.

Training camp continues Tuesday morning at Olivet Nazarene in Bourbonnais. The Bears have their first preseason game on Thursday night at Soldier Field.

Chris Emma covers the Bears, Chicago’s sports scene and more for Follow him on Twitter @CEmma670 and like his Facebook page.

Watch & Listen LIVE