The Dallas Cowboys placed center Phil Costa on injured reserve Wednesday.
Costa has missed six games with a dislocated ankle suffered Oct. 21 against Carolina. He also dealt with a back injury during training camp that caused him to leave the Cowboys' season opener after one series.
In Costa's place, the Cowboys have turned to center Ryan Cook, who played last week against Philadelphia after sitting out two games with a knee injury.
To fill Costa's roster spot, the Cowboys signed tackle Darrion Weems off Denver's practice squad.