Athletics outfielder Ryan Sweeney will miss the rest of the season to undergo surgery on his injured right knee. Sweeney was placed on the 15-day disabled list Monday with right patella tendinitis. He is expected to be ready for spring training prior to the 2011 season. "It got to a point where it was very painful for him," manager Bob Geren said. "It was recommended that to go on in the future and to feel 100 percent healthy, this was the right way to go."