Adrian Peterson has at least a sprained knee the Minnesota Vikings announced on Saturday. The running back's availability this season remains in doubt and considering the Vikings in contention for the worst record in the NFL, it would make little sense for him to play in their final game.

Frazier: sprained knee for Peterson. Will evaluate further in Minnesota

— Pioneer Press (@VikingsNow) December 24, 2011

Peterson was hurt in a pretty gruesome looking play during Saturday's win over the Washington Redskins. His left leg got caught in the turf and it twisted in an entirely unnatural way. He was immediately removed from the field. The only good news is that it looks unlikely to be a career-threatening injury, although it appeared much more serious when it happened live.

Peterson was already dealing with an ankle injury that had cost him several weeks, but he was having a decent game at the time of the injury. He had rushed for 38 yards and scored a touchdown at the time of the injury.

For more the latest updates on this injury be sure to follow this StoryStream. For more on Peterson's injury, check out Vikings blog Daily Norseman.