Kirkpatrick, the 17th overall pick in the draft, was reportedly hurt preparing for camp. The Bengals declined comment but Kirkpatrick said via his Twitter feed: "I'm sorry about my injury and im going to try my best to get back and help the team to get to a Super Bowl and once again I'm sorry#WhoDey."
The Bengals expected Kirkpatrick to compete for a starting job in training camp, but they have veteran depth to survive if Kirkpatrick isn't ready for the regular season.
Top cornerback Leon Hall is coming back from an Achilles injury.
The Bengals signed former Cowboys cornerback Terence Newman and former Texans cornerback Jason Allen along with holdovers Nate Clements, the likely starter at left cornerback, and Pacman Jones. The Bengals also drafted Shaun Prater in the fifth round of the 2012 draft.