No date has been set for the surgery for Bianchi, who is on the Royals' 40-man roster and has been in Spring Training camp.
In addition, left-handed pitcher Danny Duffy has elbow stiffness in his throwing arm and has been shut down for the time being. He's in camp as a non-roster player.
"We're backing him off of his original prescribed program and you're not going to see him pitch in any of our games in the near future, but we'll see how he progresses," Hillman said. "Medically he's fine but we're just taking the more cautious route."
Duffy also is a prized prospect. He was 9-3 with a 2.98 ERA last season for Class A Wilmington and had 125 strikeouts in 126 2/3 innings.
Bianchi, a second-round Draft choice in 2005, has been plagued by injuries before. He experienced back problems after being signed and underwent shoulder surgery in 2006.
Last season Bianchi batted a combined .308 in 128 games for Wilmington and Double-A Northwest Arkansas. He had nine homers and 70 RBIs.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.