Cornerback Dre Kirkpatrick, who was selected in the first round by the Bengals, is expected to miss up to six weeks after fracturing a bone in his knee during a workout earlier this month.
The Bengals had no comment on the injury Wednesday, but may on Thursday, after the team reports to training camp and conducts physicals.
Kirkpatrick, who was the 17th overall selection in the draft, will be put on either the Active-Physically Unable to Perform or Active-Non-Football Injury list. Both designates players who are unable to practice as camp begins due to injury but may be activated as soon as they are medically cleared.
With Leon Hall coming back from an Achilles problem, there were already questions about the position, which has been hit by injuries the last two seasons. That continued this spring as Kirkpatrick, Adam "Pacman" Jones, Shaun Prater and Nate Clements all missed workouts. Clements was out for all of the workouts due to an abdominal strain.
Defensive coordinator Mike Zimmer, though, is keeping hope alive.
"I feel good about that group. I like the athletic ability," Zimmer said during Tuesday's pre-training camp luncheon. "I like the combination of the ages. And the versatility, too, of a lot of them. I think we can find a good nucleus of guys. And we have some depth, so hopefully we can get them playing good. We've got smart guys. We've got good athletes.
"And we've got good guys."
Zimmer is hopeful that Hall can be on the field for the first practice on Friday, but Hall has not yet been cleared to return to the field.
Brandon Ghee, Terence Newman and Jason Allen are the other cornerbacks on the roster.
NOTES: One day after Zimmer said he had discussed a contract extension with the team, but said he was "not at liberty" to say whether he had one, the team announced that one had been reached. Zimmer, who his entering his fifth season here, was going into the last of a three-year extension he signed after the 2009 season. With offensive coordinator Jay Gruden having signed in January, that means both coordinators are locked up through 2014. ... The Bengals also announced the signing of third-round pick Brandon Thompson, meaning all 10 members of their draft class are under contract. The defensive tackle, who was selected in the third round, started 37 games at Clemson over his final three seasons. He had 208 tackles and 22.5 tackles for loss.