Montas, a 22-year-old right-hander, suffered a stress reaction and required a rib resection to remove his first right rib. Dr. Greg Pearl performed the operation in Dallas. Montas will begin physical therapy next week at Camelback Ranch.
The Dodgers dealt for Montas, along with infielder Micah Johnson and outfielder
Montas posted a 4.80 earned-run average in seven appearances for Chicago last season. He struck out 108 batters in 112 innings with a 2.97 ERA at double-A Birmingham.
Montas was likely bound for the Dodgers' rotation at their triple-A affiliate in Oklahoma City.