Niners RB Reggie Bush slips on concrete, injures knee

ST. LOUIS --San Francisco 49ersrunning backReggie Bushsuffered an injury to his left knee and was lost for the game after slipping on the exposed concrete beyond the team'sbench on Sunday.

Bush, who suffered the injury after a first-quarter punt return, was one of four Niners players lost to injury in the first half of Sunday's 27-6 loss to the St. Louis Rams. He said after the game that he was unsure as to the severity of the injury.

"I just slipped and fell. I'm not angry that it happened. It is what it is," Bush, who was on crutches, said after the game. "I'm not a doctor, and I'm not going to try to be one right now. We'll figure it out tomorrow after we get some pictures."

Bush, who had already missed three games this season because of a left calf strain, has an MRI scheduled for Monday.

"Trying to stay healthy has been an issue this season," Bush said. "It is what it is."

The 49ers had also lost special teams ace L.J. McCray (knee), tight end Garrett Celek (concussion) and running back Mike Davis (hand) in the first half of Sunday's game. Cornerback Keith Reaseralso suffered an ankle injury.

Bush, who was carted to the locker room, was making his first start of the season in place of the injured Carlos Hyde, who was ruled out earlier in the week with a foot injury. The only other active running backs for San Francisco were Davis and Kendall Gaskins, who was signed from the practice squad Saturday.

Davis and Gaskins rushed for a combined 2 yards on 11 carries in the first half.

Australian rugby league convert Jarryd Hayne was waived Saturday to make room for Gaskins.

Cleveland Browns quarterback Josh McCown suffered a similar fall last week when he slipped on the concrete running out of bounds and injured a shoulder.