Mitchell suffers severe knee sprain, will miss 6 to 8 weeks

Running back Elijah Mitchell’s MRI examination on Monday revealed some unexpectedly bad news for the 49ers.

Mitchell sustained a severe sprain to the medial collateral ligament in his left knee that is expected to sideline him for six to eight weeks, 49ers coach Kyle Shanahan said on a conference call with Bay Area reporters.

Mitchell likely will be placed on injured reserve for the second time this season. He could be available for the 49ers if they prolong their season with a run in the playoffs.

“He’s going to have about six weeks of frustration, but hopefully we can do our jobs here so when he comes back, we’re still playing,” Shanahan said.

The 49ers received much better news with quarterback Jimmy Garoppolo.

Garoppolo checked out OK on Monday after a hit to his left knee area from Saints defensive lineman Malcolm Roach that caused a scare.

“That was a relief that there was no serious injuries came up,” Shanahan said of Garoppolo. “I know he was pretty sore today and stuff, so hopefully he’ll work that out by Wednesday. But it’s nothing serious.”

In other injury-related news, running back Christian McCaffrey experienced knee irritation and the club will take it easy with him this week, Shanahan said.

Right guard Spencer Burford had an ankle sprain, and could return to practice later in the week.

And the 49ers are hoping that defensive lineman Arik Armstead will be available to return to practice on Wednesday and, possibly, be available for Sunday’s game against the Miami Dolphins. Armstead has been out since Week 4 due to plantar fasciitis in one foot and a hairline fracture of his ankle on the other side.

The loss of Mitchell is a big blow to the team.

Mitchell went on injured reserve after the 49ers' Week 1 game against the Chicago Bears. He missed seven games due to a torn medial collateral in his right knee.

On Sunday, he sustained an injury to the MCL of his left knee on the first carry of the second half when he bent awkwardly under the tackle of Saints defensive lineman Shy Tuttle. Mitchell remained in the game for a few more plays before exiting.

Mitchell gained a team-best 35 yards on seven rushing attempts against the Saints. On the season, Mitchell has 224 yards rushing on 40 attempts for a 5.6 average.

McCaffrey played 44 of the team’s 70 offensive snaps, as he experienced knee irritation and was in and out of the lineup. Undrafted rookie running back Jordan Mason played a season-high nine offensive snaps in the game.

McCaffrey, Mitchell and Mason were the only 49ers running backs in uniform for the game. Mason got the nod over third-round draft pick Ty Davis-Price due to his contributions on special teams. The team also has the option of elevating veteran Tevin Coleman from the practice squad.

The 49ers traded leading rusher, Jeff Wilson Jr., to the Miami Dolphins, this week's opponent, after acquiring McCaffrey from the Carolina Panthers. The 49ers received a fifth-round pick in return for Wilson.

San Francisco averted disaster at the quarterback position when Roach went low and hit Garoppolo’s left knee after he threw an 11-yard completion to receiver Brandon Aiyuk. Garoppolo appeared to be in immediate pain but remained in the game.

It was the same knee in which Garoppolo sustained a torn ACL in Week 3 of the 2018 season.

“There's no place for that,” Garoppolo said on Sunday of the play on which Roach was penalized for unnecessary roughness. “But, no, I'm all right. A little sore, but nothing bad.”

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After Garoppolo went down, backup quarterback Brock Purdy started warming up — just in case.

“He looked banged up a little bit,” Shanahan said. “We don't get to talk to him right at that time and he was a little slow to get up and right when that happens, we tell our guys to get loose just in case.”

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