The procedure was performed in Vail, Colo., by Dr. Marc Philippon, the same doctor who performed hip surgery on Yankees third baseman Alex Rodriguez and former Nats closer Mike MacDougal.
Detwiler, 23, is scheduled to arrive in Viera this weekend. He will begin a throwing program in six weeks.
According to manager Jim Riggleman, Detwiler started feeling pain about a week ago while throwing the baseball. Detwiler then went to the trainers and had an MRI on the hip. The trainers didn't like what they saw, so Detwiler went to Colorado to see Dr. Philippon, who confirmed that surgery was needed.
Detwiler was scheduled to compete with a least 10 pitchers for the final two spots in Washington's rotation.
Detwiler, the Nationals' first pick in the 2007 First-Year Player Draft, made his Major League debut last season and went 1-6 with a 5.00 ERA in 15 games with Washington, but had a 1.90 ERA during the month of September.
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.