Team officials say Lidge had surgery Wednesday to remove loose bodies in his right knee. The right-hander also underwent elbow surgery on his throwing arm in November.
Phillies trainer Scott Sheridan on Thursday said Lidge should be able to begin throwing again in 10 days but it is not certain when he'll be ready to pitch in a game.
Lidge spent time on the disabled list last season with a sprained right knee.
Lidge had a poor season last year, converting 31 of 42 save opportunities with a 7.21 ERA in the regular season. His 11 blown saves led the majors.