KANSAS CITY, Mo. -- Royals pitcher Nate Karns will undergo surgery next week to remove a rib that's causing nerve pain in his forearm. He will miss the remainder of the season, though he expects to be ready by the time spring training rolls around.

Karns was acquired from the Seattle Mariners in the offseason and was off to a promising start in Kansas City when his forearm started hurting. The right-hander was placed on the disabled list on May 24 while the Royals began trying to determine the source of his nerve discomfort.

After other therapies failed to ease the pain, Karns consulted a specialist in thoracic outlet syndrome, which is caused by muscles attached to the uppermost rib that create a compression of nerves.

Wednesday's surgery in Dallas will remove one of his ribs, alleviating some of that pressure.