The actress, who plays Lady Sif in Thor, was in the U.K. to shoot the superhero blockbuster's sequel when she ended up in hospital after a bad fall.
Taking to Twitter.com shortly after the accident, she tweeted, "I sustained a pretty horrible injury. I'm lucky I'm not paralyzed. Thank you (with all of my heart) to those who've looked after me."
The 28 year old was forced to sit out of production for weeks while recovering, and now Alexander admits the fall was far more serious than she initially let on.
Sh recalls, "It was raining, it was dark outside, it was, like, five in the morning - and I went down a metal staircase and slipped and slipped a disc in my thoracic spine and chipped 11 of my vertebra... I knocked my left shoulder out of place and tore my rhomboid (muscle) on my right side... It took me out of filming for a month."
But the beauty insists she is already on the mend, telling the New York Post, "I heal really fast. Everyone thinks it's really funny to tease me about staircases now that I fell down one... I'm walking in heels again though, so that's a good sign."