The injury, sustained on Falcons quarterback Matt Ryan's eight-yard rush, saw Ratliff go to the ground with an apparent lower extremity injury. Ratliff was unable to leave the field immediately as trainers rushed to examine him.
At half, the Cowboys and Falcons are tied at six, with little offense emerging on Sunday night.
For the season, Ratliff has recorded 10 tackles, six of which were solo. He has also defending one pass on the year. In the Cowboys loss to the New York Giants last weekend, Ratliff recorded five tackles.
The eight-year NFL veteran out of Auburn has 222 tackles in his career, and has forced four fumbles while playing his entire career to date in Dallas.
Ratliff has yet to return to the game following the injury.