Mitchell was forced out of Sunday's game against the Saints due to a knee injury.
Mitchell dealt with knee irritation during the stretch run of last season and also sat out Weeks 2-8 of this year due to an MCL sprain in his right knee. The current concern will keep him sidelined for the rest of Week 12, capping him at seven carries for 35 yards and two catches (on two targets) for eight yards. Jordan Mason will move up to No. 2 on the RB depth chart for the 49ers behind Christian McCaffrey for as long as Mitchell is sidelined.