Vonn later tweeted she had an "acute facet (spinal joint) dysfunction. I got compressed on the 6th gate and my back seized up,” CNN reported.
Vonn finished 24th in Saturday's race, more than a second behind winner Jasmine Flury of Switzerland.
The Pyeongchang Olympics in South Korea will be held Feb. 9-25. The American star won the downhill title at the 2010 Vancouver Games but missed the 2014 Sochi Games because of injury.
Unfortunately I will not be able to race today. I am extremely disappointed but my biggest goal this season is the Olympics and I need to take care of myself now so I can be ready for next week, and more importantly, for February. As always, thank you for the well wishes ❤️🙏🏻