George W. Bush has knee surgery in Chicago at Rush Medical Center

CHICAGO (WLS) -- President and Mrs. George W. Bush were back in Chicago this weekend. President Bush's left knee was partially replaced on Saturday morning at Rush University Medical Center.

Both this operation and the partial right knee replacement he had over Memorial Day weekend were outpatient procedures performed by Dr. Richard Berger of Midwest Orthopaedics at Rush. President and Mrs. Bush are on their way back to Dallas Monday morning.

"He's looking forward to getting back on his mountain bike in a few weeks," a spokesperson said in an email.

In May, Bush participated in a three-day, 100-kilometer mountain bike ride with wounded veterans in Crawford, Texas. The George W. Bush Presidential Center released a photo of the former president leading the group.