Who knew that belly buttons were injury-prone? Former UFC middleweight champion Rich Franklin explained that his recent absence from the Octagon was due to an umbilical hernia surgery.

In January 2009, Franklin noticed that his belly button looked different - sticking out oddly - but he did not think much of it at first, especially since it did not cause him any pain.

"When I looked at it, I thought, 'That doesn't look good,'" he told TSN. "I just thought that's what happens, you get older. Things start growing hair or whatever, they start popping out. That was my explanation for it. I thought it's no big deal. If I don't feel pain, then it can't be anything bad."

However, by September, his belly button had gotten worse. Franklin was diagnosed with an umbilical hernia, meaning that his belly button was tearing from the lining of his stomach. This condition gets worse if left untreated, and since Franklin did not have a fight on the horizon, he chose to undergo surgery to correct it.

According to TSN, the surgery fixed two tears: one at the top of Franklin's belly button, and the other in the stomach lining. While the surgery was successful and he only felt pain for one week after, he was sidelined for a month and a half for fear of risking another tear.

Healthy again, up next, Franklin will take on former UFC light-heavyweight champion Chuck Liddell. The two will meet at UFC 115 on June 12 in Vancouver, Canada. Franklin took the place of fellow former champion Tito Ortiz, who was forced out of The Ultimate Fighter 11 coach's bout.