Former U.S. President George W. Bush has undergone surgery for a partial replacement of his left knee, six weeks after having a similar procedure on his right knee, his spokesman said on Monday.
The outpatient procedure was conducted on Saturday at Rush University Medical Center in Chicago by Dr. Richard Berger of Midwest Orthopedics, who had worked on Bush's right knee in late May.
Bush, who turned 68 a week ago, is an active mountain biker and golfer.
Each spring, Bush hosts about 20 wounded soldiers on a three-day, 100-km ke ride, part of the George W. Bush Institute's military service initiative.
Bush first started the rides at his ranch in Crawford, Texas, four years ago.
He has also taken up painting since returning to his home state of Texas after leaving the presidency in early 2009.
"President and Mrs. Bush are on their way back to Dallas this morning," said Bush spokesman Freddy Ford. "He's looking forward to getting back on his mountain bike in a few weeks."
President Bush swapped his running shoes -- he suffered from runner's knee -- for biking shoes in 2003.
While president, most of his biking occurred at the Secret Service facility in Beltsville, Maryland, but he also squeezed in cycling trips to the Marine base at Quantico, Virginia, and Camp David in Maryland.
Some information for this report provided by Reuters and AP.