Updated

U.S. Olympic gymnast Shawn Johnson was slated to follow up her two silver medals at the 2008 Summer Olympics by competing in the 2012 Summer Olympics. Johnson, however, has decided that she will hang up the unitard and retire from professional gymnastics at the age of just 20 years old.

In 2010, Johnson tore her ACL while skiing and had to have reconstructive surgery on her knee. Johnson announced in May of 2010 she would hope to be healthy by the time the 2012 Olympics rolled around to compete for the United States. Unfortunately, due to issues with her injured left knee, Johnson has decided to retire.

"I still have the heart, drive, and desire to compete and help the USA at the London Olympics," Johnson said in a press release on her Facebook page. "Unfortunately, it has become obvious that my left knee is not able to sustain the demands of gymnastics any longer. All I can do now is gracefully retire and thank everyone who has believed in me and my journey."

"I am announcing this now so the focus for the next three weeks will be on the incredibly talented gymnasts who are trying to make our 2012 Olympic Team," said Johnson. "I have had the honor to train and compete with them, and I am excited to join the gymnastics family and fans in cheering them on to victory. I will be there with every ounce of pride and energy to cheer on my girls and Team USA."

Now that Johnson has retired, she plans to focus on things like college and her charity work.