Detroit Lions running back Mikel Leshoure injured his Achilles last Monday. Immediately the Lions announced Leshoure would miss the entire 2011 season because of the injury. They didn't make it official until Sunday, though. That's when they announced that Leshoure was placed on injured reserve.
As Philip Zaroo points out at MLive, Leshoure will still count against the Lions' 90-man roster despite being placed on IR. Once the final round of roster cuts happens he will no longer take up a spot on the roster. For now the Lions don't want to risk exposing him to waivers to free up a roster spot, so he will still count against it.
To make room on the roster for Madison the Lions released offensive tackle Tony Ugoh, who missed practice on Wednesday and Thursday for an unknown reason. There was talk that he was considering retirement, but it's not clear what was the cause of Ugoh's absence. In any case, he's gone for good now.