Former President George W. Bush underwent his second knee replacement surgery in two months at a hospital in Chicago over the weekend, according to his spokesman. 

The former Republican president had the outpatient surgery on his left knee at Rush University Medical Center on Saturday and is traveling back to Texas on Monday. 

In late May, he had a knee replacement surgery on the opposite knee. 

Bush, 68, is an avid bike rider. In the weeks before his first knee replacement surgery, he hosted a 100-kilometer, three-day bike ride at his ranch to honor injured service members from Iraq and Afghanistan.

"President and Mrs. Bush are on their way back to Dallas this morning. He's looking forward to getting back on his mountain bike in a few weeks," spokesman Freddy Ford said in a statement. 

Last year, Bush underwent heart surgery to open a blocked artery.