Thinking of being a world-class skier?? Lindsey Vonn might have ya reconsidering ... 'cause she just posted a pic of the knee she tore up flyin' down a mountain -- and it's DISGUSTING.
Vonn -- one of the greatest female skiers ever -- ripped up her knee in a crash during training last November ... and shredded her LCL so badly, she required surgery.
Lindsey says she put off the operation until now 'cause she had some obligations to fill ... and it's pretty easy to see why she waited so long to go under the knife.