Hidalgo, one of 13 Astros on the disabled list this season, has inflammation resulting from loose cartilage. The Astros said it was caused by a congenital condition that caused the kneecap not to properly join together.
He will have the operation Thursday in Houston.
Hidalgo, 24, hit .227 this season with 15 homers and 56 RBIs. He also has 15 outfield assists.
Astros outfielders Derek Bell (left groin) and Moises Alou (left knee surgery) also are on the disabled list, and Alou may not play at all this season following a treadmill accident prior to spring training.
Also Tuesday, Astros infielder Bill Spiers returned to Houston and will have a cortisone injection in his back Wednesday. Spiers, who also had a cortisone injection during spring training, is expected to be sidelined until Sunday.
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