The surgery was done in Gulf Breeze, Fla., by Dr. James Andrews, who performed the same procedure on Medlen in August 2010.
The injury is one of several for Braves pitchers this spring.
Brandon Beachy had his ailing elbow examined by Andrews on Monday and was expected to head to Los Angeles to get another opinion from Neal ElAttrache, the team's physician.
Medlen and Beachy were expected to be stalwarts of the Braves' rotation. After they went down, the team hastily signed free agent Ervin Santana to a $14.1 million, one-year deal.
Santana will make his spring debut Thursday against the New York Mets, Braves manager Fredi Gonzalez announced.
Also Wednesday, Braves catcher Evan Gattis was scratched with a mild right quad strain.
Information from the Associated Press was used in this report.