The procedure had been a near-certainty since Arrieta was put on the disabled list on Aug. 1 and it was reaffirmed after he had a CT scan and MRI arthogram -- which involves contrast dye -- and visited orthopedic surgeon Dr. Lewis Yocum in Los Angeles early Friday.
The only other option for Arrieta -- who is experiencing pain in the area and has struggled with his command -- would have been to get cortisone shots in the area frequently during the season, but the right-hander said in a text message he didn't want to "mask an injury," and would prefer to just have the spur removed.
The full recovery time is 2 1/2 months and, given the surgery's timing, Arrieta will be able to have a normal offseason throwing program and is expected to be at full strength next Spring Training.
The 25-year-old Arrieta went 10-8 with a 5.05 ERA in 22 games. His 10 wins lead the Baltimore staff.
Brittany Ghiroli is a reporter for MLB.com. Read her blog, Britt's Bird Watch, and follow her on Twitter @britt_ghiroli. This story was not subject to the approval of Major League Baseball or its clubs.