Royals officials said Hochevar underwent a scalenectomy, a surgical procedure that divides or removes a portion of the anterior and/or middle scalene muscle. Hochevar also had a rib resection of an upper rib.
The procedures are done to relieve nerve pressure, a common symptom of thoracic outlet syndrome.
Hochevar, 33, finishes the season 2-3 with a 3.86 ERA in 40 games. But in his last 12 outings, when he began to experience numbness in his fingers and hand, opponents had a .310 batting average against him and his ERA was 7.84.
Hochevar has a mutual option for 2017, but the Royals never have exercised a mutual option under this regime, so he all but certainly will become a free agent this fall. There is a $500,000 buyout to his contract.
Jeffrey Flanagan has covered the Royals since 1991, and for MLB.com since 2015. Follow him on Twitter @FlannyMLB. This story was not subject to the approval of Major League Baseball or its clubs.