Cardinals place RB Trey Benson on injured reserve

The Cardinals aren't certain about running back James Conner's availability for Sunday. He exited the Week 17 game after aggravating his knee injury.The Cardinals know they won't back backup running back Trey Benson. The third-round rookie landed on injured reserve Tuesday with his ankle injury, ending his season. Benson had missed the past two games.He rushed for 291 yards on 63 carries this season with a touchdown, averaging 4.6 yards an attempt as Conner's main backup. He also had six catches for 59 yards.The Cardinals signed offensive lineman Nick Leverett from the practice squad in a corresponding move. They replaced Leverett on the practice squad by re-signing running back Hassan Hall, who was with the team in the preseason.Veteran running back Michael Carter, who remains on the practice squad, has an elevation remaining and would start if Conner is out against the 49ers.