Stafford acknowledged the injury after the game. The third-year quarterback completed 33 of 63 passes for 329 yards, one touchdown and four interceptions. Stafford struggled with accuracy issues throughout the game.
"It's fractured but it's not bad," Stafford said, adding that a wind with gusts around 30 mph created the most difficulty.
He didn't say when the injury occurred.
Stafford sported a glove to help him get a better grip on the football.
"I felt fine with it. I felt like I made some real good throws with it and obviously made some tough throws with it," he said.
Kevin Seifert covers the NFC North for ESPN.com. Information from The Associated Press contributed to this report.