Best, Detroit's top running threat, is done for the 2011 season. (Getty Images)

Posted by Ryan Wilson

The Lions announced Friday that they would place running back Jahvid Best on injured reserve ending his season. The move won't come until next week, when the NFL office processes the transaction following the completion of all Week 12 games, according to CBSSports.com Rapid Reporter John Kreger.

Best hasn't practiced or played since suffering his second concussion of the season in Week 6.

Without Best, Detroit's running game has been among the most inconsistent in the NFL. It was so bad that the Lions signed street free agent (and former draft pick) Kevin Smith several weeks ago to bolster the rushing attack and he responded with a 140-yard effort against the Panthers in Week 11. Smith suffered an ankle injury during Thursday's Thanksgiving Day loss to the Packers and his status for next Sunday is unclear.

Even though Best hasn't played since October 16, he still leads the Lions in rushing (84 carries, 390 yards). At the time of his injury, he also ranked third on the team with 27 receptions for 287 yards, and he was coming off a 163-yard Monday night performance against the Bears that included an 88-yard touchdown run.

“From the outset, we have been appropriately cautious and have followed all medical protocol with respect to Jahvid’s injury,” Lions coach Jim Schwartz said Friday, according to DetroitLions.com. “We look forward to his continued improvement and eventual return to the field.”

The Lions face the Saints next and they could go into that game with Maurice Morris and Keiland Williams as their two primary running backs.

Oh, and there's a chance they could soon be without their defensive enforcer, too.

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