Caitlyn Jenner celebrated her Christmas while recovering from a surgery that she was putting off over the last 25 years; what happened to her?

Taking to her Instagram account over the weekend, the 72-year-old gubernatorial hopeful shared a video, saying she underwent a procedure a few weeks ago.

While greeting 12.1 million followers on the social media platform, the reality star wrote in the caption, "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." (watch the full video below)

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In the video, which appears to be taken prior her surgery, Jenner revealed "Guess what I'm doing today, I'm getting my knee replaced."

"I've been putting this off for 25 years and I'm finally going to do it today."

The former Olympian assured her fans that she would post further updates regarding her recovery process.

Why do People Undergo Knee Replacement Surgery?

According to John's Hopsking Medicine's website, knee replacement is often called as "arthroplasty," wherein a procedure needed to happen when a knee is damaed by arthritis throughout the years.

The operation is suggested for people who are experiencing severe arthritis. Metal or plastic parts are used as a substitute to the original bone.

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Aside from inflammation of the arthritis, the procedure could also be used for damages caused by trauma or injury, and many more.

Knee replacement surgeries are common to famous celebrities and athletes, among those people are John Elway of the National Football League's Denver Broncos.

After playing throughout his career, he underwent the procedure in 2007.

Caitlyn Jenner's Other Surgeries

According to Hello Magazine, Jenner underwent several aesthetic surgeries after coming out as a transgender woman. Doctors enhanced her feminine features through facial feminization surgery, which contours the facial structure, jaw, forehead chin and more.

Two years after coming out, the "Keeping Up With The Kardashians" star also undergone sex reassignment surgery, which she wrote in her book "The Secrets of My Life."

"The surgery was a success, and I feel not only wonderful but liberated," she wrote. (via Radar Online)

Despite starting taking hormones at the age of 39 which led her to develop breasts, she also have breast implants and rhinoplasty.

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