Reggie Bush fought the wall and the wall won.

Denny Medley USA TODAY Sports

San Francisco 49ers running back Reggie Bush was carted off the field with a left knee injury in the first quarter of Sunday's game against the St. Louis Rams.

Bush was injured at the end of a punt return, losing his footing after he was pushed out of bounds and slid on the concrete beyond the sideline feet-first into the wall. The 49ers listed Bush as questionable to return.

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It marked the second straight week a player was shaken up after skidding on the concrete at the Edward Jones Dome. Cleveland Browns quarterback Josh McCown hit his head and elbow on the wall last Sunday against St. Louis but was able to return to the game.

San Francisco already is without starting running back and leading rusher Carlos Hyde, who is inactive with a foot injury.

The absence of Bush, who has missed three games this season due to calf injuries, leaves the 49ers with rookie Mike Davis and Kendall Gaskins -- a practice-squad promotion this week -- in the backfield.

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