Lindsey Vonn withdrew from the Winter Games because her surgically repaired knee is too unstable to compete after reinjuring it, leaving the U.S. Olympic Team, broadcaster NBC and sponsors without their most marketable athlete.

Vonn, the top-earning U.S. skier in history and the four- time World Cup overall champion, won't defend her Olympic downhill skiing gold medal in Sochi, Russia, after deciding to undergo surgery on her right knee, she said today in a Facebook post.

Vonn will have surgery shortly and is expected to recover in time for the 2014-15 World Cup ski season, she said.

“I did everything I possibly could to somehow get strong enough to overcome having no ACL, but the reality has sunk in that my knee is just too unstable to compete at this level,” Vonn said.

The 29-year-old Vonn tore her anterior cruciate and medial collateral ligaments in February and then re-injured the surgically repaired knee on Nov. 19. She returned to competition two weeks later, finishing 40th at Lake Louise, Alberta.

The training accident at the U.S. Ski Team's Speed Center at Copper Mountain, Colorado, caused ligament sprains, “which coupled with the torn ACL, has made it impossible to stabilize her knee and be ready to safely ski again next month,” her spokesman, Lewis Kay, said in an e-mailed statement.

With sponsorship deals from companies including Procter & Gamble Co., Under Armour Inc., Red Bull GmbH and Rolex Group, Vonn was being marketed as the biggest star of the competition that will run from Feb. 7-23.

“While this is certainly a blow given her notoriety and familiarity to fans, the Olympics always seems to benefit from — if not create — new stars and media darlings,” David Carter, executive director of the Sports Business Institute at the University of Southern California, said in an e-mail. “Other compelling stories will emerge, and they will gain traction with fans and consumers.”

NBC spokesman Christopher McCloskey didn't immediately return an e-mail seeking comment.

With less than a month remaining before the Olympics, corporate marketing efforts for Vonn and other athletes are already in “full go-mode” and are unlikely to be affected, according to Rick Burton, professor of sports management at Syracuse University.

“What will be really interesting is whether or not we see a ratings slippage,” Burton said in a telephone interview. “That's hard to predict based on whether or not she was going to be competitive. Had she gone but not been competitive, NBC would have been trying to capture some of the heartache, trying to spin a story of how heroic she was in trying to go on a bad leg.”

The absence of Vonn, who also has gained fame by dating world No. 1 ranked golfer Tiger Woods, will leave Comcast Corp.'s NBC working to create a new fan favorite, Burton said.

“Someone has to be developed as a media darling,” Burton said. “They've got a month to get ready to get her replacement, who hopefully for them is photogenic and at least a top 10 skier to build a story around.”

Vonn has won six straight World Cup downhill season titles.

“In looking ahead, I have every ounce of confidence that Lindsey will be in the starting gate next World Cup season ready to compete,” Bill Marolt, president and chief executive officer of the U.S. Ski and Snowboard Association, said in a statement. “She knows the hard work it takes to get to the top and still has significant goals to achieve in what has been an incredible career.”

With a women's ski team that includes veteran Julia Mancuso, a three-time Olympic medalist, the U.S. squad still has plenty of experience, Marolt said.

“Now is the time for those athletes to step up towards our best in the world vision,” he said.