The 55-year-old former Calvin Klein model recalled how she flew off a balance board in a New York City gym and landed in such a way that it shattered her thigh bone.
Shields confessed she thought she was paralyzed because she couldn't feel her toes at the time.
The actress said she wasn't sure she'd ever walk again and needed her first surgery to insert two metal rods "one from the top of my hip down, and another across into the hip socket," she told People magazine.
Shields later needed a second surgery after the top part of her femur popped out. This procedure included an additional five rods and a metal plate to the bone.
The mother of two's journey to recovery didn't end there. After spending two-and-a-half weeks in the hospital she went home only to return because of a staph infection and needed emergency surgery on the IV site where she had three blood transfusions.
"At first they feared it might be MRSA [a type of bacteria resistant to antibiotics]," Shields said. "Thank God it wasn't. If it had been, my doctor said it would have been a race against time. That's how you can become septic. It seemed unthinkable."
Her daughters, Rowan, 17, and Grier, 14, and her husband Chris Henchy couldn't visit because of COVID-19 protocols in the hospital.
"I'll never forget how hard the doctors and nurses worked and hearing their stories about COVID," she recalled. "I have asthma but I kept thinking, 'I feel blessed I can breathe.'"
Shields said when she returned home the second time she couldn't "even stand on my leg or go up a step. I need to relearn how to even walk. The feeling of helplessness is shocking."
"If anything, I'm a fighter," she added. "This is my journey, and if it took me breaking the largest bone in my body, then recovery is something I want to share. We have to believe in ourselves and encourage one another. There's no other way to get through life, period."