"There's definitely at least one torn ligament -- I don't think we can say multiple until we get the tests back -- but he'll need surgery," Lions coach Jim Schwartz said. "We'll know more in the next few days about his status going into next season."
Schwartz didn't have as much information on rookie quarterback Matthew Stafford, who missed the Ravens game after aggravating a shoulder injury the previous week in Cincinnati.
"Right now, things are unchanged, but we don't know how things will progress as the week goes on," he said. "Last week, he was very sore and he couldn't play, and if he stays that sore, he won't play again on Sunday."
Veteran Daunte Culpepper would start for the fourth time this season if Stafford can't go.
The Associated Press contributed to this report.