Chris Johnson's comeback story hits a bump, with fractured tibia

Who would have guessed three months ago that an injury to running back Chris Johnson would have a serious impact on the Super Bowl picture?

Johnson, out of a job all summer until he was signed by the Arizona Cardinals in mid-August, has a fractured tibia, or shinbone, according to Fox Sports' Jay Glazer. He'll be out an "extended period," Glazer said, but the team is gathering information to see how long he'll be out.

It's a tough blow, because Johnson has been one of the league's biggest surprises. He is the fourth-leading rusher in the NFL with 814 yards, although he had three quiet games in a row before the injury.

The Cardinals were dealt another blow to their running game Monday, because Andre Ellington is dealing with a turf toe. Intriguing rookie David Johnson, who has seven touchdowns in a limited role, will likely step in for at least a few weeks.

It has been a long road back for Chris Johnson, once a huge star with the Tennessee Titans who looked like he might be done in the NFL, especially after he was shot in the shoulder this offseason. We'll see if he can come back for a second time this season, and be a factor for the NFC West-leading Cardinals in the playoffs.

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Frank Schwab is the editor of Shutdown Corner on Yahoo Sports. Have a tip? Email him at shutdown.corner@yahoo.com or follow him on Twitter! Follow @YahooSchwab