Lions quarterback Jon Kitna suffered a sprained left knee in the fourth quarter of Sunday's loss to the 49ers, according to Detroit Free Press. "It feels pretty bad right now," Kitna said Sunday night. "They say it doesn't feel like anything structural right now." Kitna said the injury was a culmination of four or five tough hits. "Sometimes when you have kind of a bruise on your knee or some trauma to it, and then it happens again, the pain is pretty excruciating for a minute, and then it subsides," Kitna said. "And that was kind of what was happening."