EDEN PRAIRIE, Minn. -- The Minnesota Vikings made a handful of roster moves on Tuesday to suggest they're going to be scrambling for healthy safeties on Thursday night in Arizona.

The Vikings brought back defensive back Shaun Prater, who appeared in 18 games in 2013 and 2014 with the team, and brought Anthony Harris up to the active roster. They put safety Antone Exum on injured reserve (a league source told ESPN on Monday that Exum fractured a rib and sustained an injury to the AC joint in his shoulder on Sunday) and released defensive end Justin Trattou. They also brought linebacker Terrance Plummer back to the practice squad, with Anthony Barr possibly missing Thursday's game because of a groin injury.

The moves come as the Vikings scramble to put together a healthy defense for Thursday's game against the Cardinals. Safeties Harrison Smith, Andrew Sendejo and Robert Blanton were all out of practice with injuries on Monday, and it's possible the Vikings will be without two or three of them against Arizona. Exum was going to miss 2-3 weeks, according to the league source, but given the situation, the Vikings couldn't afford to wait that long.

It's also possible the Vikings will be without nose tackle Linval Joseph again on Thursday, as they take on the league's top-ranked offense in Arizona. What would have been a tall task for a healthy defense now looks like it will require some ingenuity.