The reconstructive surgery to the ulnar collateral ligament in Anderson's left elbow was called successful by Dr. James Andrews, who performed the operation in Pensacola, Florida, the Athletics said in a statement.
Anderson, 23, was placed on the disabled list on June 7 with a sore elbow. After treatment by Andrews in June, it was determined the left-hander needed surgery.
He compiled a 3-6 record with a 4.00 earned-run average in 13 starts this season.
(Reporting by Gene Cherry in Raleigh, North Carolina; Editing by Frank Pingue)