Indianapolis, IN -- (Sports Network) - The Indianapolis Colts have placed rookie running back Mike Hart on injured reserve because of a knee injury.

Hart was hurt during last Sunday's game against Baltimore. The sixth-round pick from Michigan had just nine yards on two carries in limited action this season.

With Joseph Addai also nursing a hamstring injury that forced him out of last week's game, the Colts signed a pair of running backs -- Clifton Dawson as a free agent and Chad Simpson off the team's practice squad. Dawson was released by the Colts in August.

The Colts, who added defensive tackle John McCargo to the active roster following his acquisition from Buffalo before Tuesday's trade deadline, also waived defensive tackle LaJuan Ramsey and defensive back Nick Graham.

In addition, running back Lance Ball was signed to the practice squad.