The Olympic gold medalist was bothered by her aching knees during the season, but elected to keep it hidden.
She said Saturday after skiing out in the giant slalom at U.S. Championships that an initial checkup indicated probable trouble in both knees. She's scheduled for an MRI on Monday.
Vonn doesn't think the injury will be "too big of a deal" and hopes the injury "won't set me back too far."
It was quite a season for Vonn, who amassed the most points ever by a female skier. She was chasing Hermann Maier's record mark of 2,000 points, but finished shy at 1,980.
(Copyright 2012 by The Associated Press. All Rights Reserved.)