SANTA CLARA (CBS SF) — Raheem Mostert, the lead running back for the San Francisco 49ers, announced on social media Tuesday that he planned to undergo season-ending knee surgery.

In a statement posted on his Twitter account, Mostert, who chipped off a piece of cartilage in his knee during the 49ers game against the Detroit Lions Sunday, wrote that he decided to get the surgery after weighing his options and consulting multiple doctors.

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“This gives me the best possibility at coming back 100%,” Mostert wrote. “I have ALWAYS come back stronger and I will this time, too!”

GLENDALE, ARIZONA – DECEMBER 13: Running back Raheem Mostert #31 of the San Francisco 49ers rushes the football against the Washington Football Team in the third quarter of the game at State Farm Stadium on December 13, 2020 in Glendale, Arizona. (Photo by Christian Petersen/Getty Images)

Mostert, 29, signed to the 49ers in 2016, after being picked up by five different teams over two years. Injuries shortened his 2017 and 2018 seasons, but he broke out during the 49ers 2019 season, racking up 772 rushing yards and eight touchdowns. He was an essential part of the team’s running attack, which helped the team reach the Super Bowl that year.

In 2020, after requesting a trade and renegotiating his contract, Mostert was injured again during the second game of the season. Despite some great play, he spent the season going off and on injured reserve, and he played just eight games — first injuring his knee and then a high ankle sprain, and then before the end of the season, he was out after he broke his arm. He ended the 2020 season with 521 rushing yards and two touchdowns.

Mostert becomes a free agent in 2022.

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The team had already placed Mostert on the injured reserve after Sunday’s game in Detroit, thinking he would return after eight weeks. It appeared Tuesday that Mostert made the decision to undergo the surgery without consulting his team as 49ers Coach Kyle Shanahan said at a press conference the day before that the team expected Mostert to return before the end of the season.

“Fortunately, I think we’ll get Raheem back later this year, so we’ve got to make sure that guys hold down the fort while he’s gone,” Shanahan said when asked about his team’s running back situation.

Mostert is one of four running backs on the 49ers. At this point the team is down to two active running backs — Elijah Mitchell and JaMycal Hasty — as veteran RB Jeff Wilson is still on injured reserve due to a torn meniscus. While Shanahan says he expects Wilson to be able to play by the middle of the season, the team can also bring up 2021 third-round draft pick Trey Sermon from the practice squad.

UPDATE: Following Mostert’s announcement, the 49ers said they signed former Detroit Lions running back Kerryon Johnson.

Read Mostert’s full statement:

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