AceShowbiz - Caitlyn Jenner spent Christmas recovering from a surgery. The "Keeping Up with the Kardashians" star told her online followers she checked herself into a hospital earlier this month to undergo a knee replacement surgery.

The Gold-winning Olympian wished everyone a happy holiday, "Merry Christmas! This year I got a new knee. 11 days ago I had knee replacement surgery. I'll keep you posted on my progress! Stay tuned. Enjoy your Christmas! Stay healthy and happy."

The 72-year-old retired athlete said the procedure was long overdue, "Yes, I'm getting my knee replaced. I've been putting this off for 25 years, and I'm finally going to do it today!"

Caitlyn Jenner once played college football for the Graceland Yellowjackets, but she quit due to a recurring knee injury. She then switched to decathlon.

In a docu-series earlier this year, she talked about struggling with her identity during her sports career. "I spent my entire life hiding," she said. "I didn't want people to know me, and know who I was."

"I was an Olympic Champion, the greatest athlete in the world," she added. "But I was still the same old person with all the same old issues."

Despite being a trans woman herself, Caitlyn was against trans females competing in women's sport. "I oppose biological boys who are trans competing in girls' sports in school," she said. "It just isn't fair, and we have to protect girls' sports in our schools."

She was also "a traditionalist" when it came to marriage. "I'm older than most people in the audience, and I kind of like tradition, you know, and it's always been a man and a woman," she once told Ellen DeGeneres.

"If that word 'marriage' is really, really that important to you, I can go with it," she added.

Ellen found Caitlyn's stance on same-sex marriage "confusing." "She still has a judgment about gay marriage," the host said in an interview with Howard Stern. "And I said, 'You're wanting people to understand and accept you … and you still have a judgment about gay people and marriage.' "