Reggie Bush placed on season-ending IR after tearing MCL

San Francisco 49ers running back Reggie Bush will undergo season-ending surgery on a torn MCL, according to ESPN's Adam Schefter. The team officially placed him on injured reserve Tuesday and signed Pierre Thomas for running back depth.

Bush left the team's game against the St. Louis Rams with what was initially believed to be a torn ACL. Early against the Rams, Bush was returning a punt and got pushed out of bounds toward the sideline wall, which is surrounded by concrete. Bush slid down to the ground on the concrete and was immediately assisted by the 49ers' training staff.

Bush stayed down and the cart was brought in to take him to the locker room. The 49ers later announced that he was officially out for the rest of the game with a knee injury.

He hit the concrete hard before going into the wall:

Last week, Cleveland Browns quarterback Josh McCown was injured after running into the wall on the Rams' sideline as well.

Bush started the game at running back for the 49ers due to Carlos Hyde missing Sunday's game with a foot injury. Bush has just eight carries for 28 yards on the season, plus four catches for 19 yards. Behind him on the depth chart are rookie Mike Davis and Kendall Gaskins, who was elevated from the practice squad on Saturday after the team released Jarryd Hayne. Davis, though, is also injured and will have surgery on his broken hand on Tuesday.

Hayne was signed back to the practice squad Monday evening.