Since then, she's been in debilitating pain. But the chance to dance with the stars finally forced Grey to get treatment.
"The collision was so intense, that the ligaments were ripped from the back of my neck," Grey says. "I'd have a headache for four days where I could barely open my eyes. I couldn't do anything that involved a whole section of my body because it would send my neck into spasm."
Grey went to see Los Angeles-based spine specialist Dr. Robert Bray.
Bray put her back together again, removing a disc and screwing a titanium plate around her spinal cord.
But Bray spotted something else. Grey's thyroid was enlarged. It turned out to be cancer.
More surgery followed and she's OK now.
Grey now says getting her body and her health on track for "Dancing With the Stars" may have saved her life.