As landmark TV show The Big Theory nears its 15th birthday, a new book is sharing secrets from behind the scenes of the hit series.

Speaking to Entertainment Tonight, The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series author Jessica Radloff and series creator Chuck Lorre revealed how star Kaley Cuoco nearly lost her leg a decade ago.

"It was very serious and Kaley still has a really hard time talking about it," Radloff said.

Cuoco was involved in a horseback riding accident in 2010. The horse she was riding got spooked, bucked her off and ran over her left leg.

"Thank God Kaley came out of this OK. The reason she came out of it OK is because of Chuck. Chuck helped get her the care at Cedars-Sinai that she needed and... when she was in recovery, he would come and play his guitar for her and bought her a rocking horse and said, 'This is the only horse you're now allowed to ride,'" Radloff continued.

Lorre called Cuoco's injury was "devastating."

"There were so many things that happened that had they not happened, she might've lost the leg," he said.

Despite the seriousness of her injury, Lorre noted Cuoco only missed one episode. Additionally, the actress only used a stunt double one time, during an episode in which Cuoco had to run back to her character's room.

The Big Bang Theory: The Definitive, Inside Story of the Epic Hit Series is available now. The book features several other stories and revelations, such as which cast member wanted the show to end and which actor turned down their role multiple times.

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