SEATTLE - Oakland right-hander Jarrod Parker, recovering from Tommy John surgery more than a year ago, broke a bone in his elbow during a minor league game.

Pitching in a rehab game for Triple-A Nashville on Friday, Parker threw wildly to the plate and collapsed just off the mound. He rolled around in pain and had to be helped off the field.

X-rays and a CT scan at Vanderbilt University Medical Center on Saturday revealed a fracture of the medial epichondyle bone. It's in the area where the surgery was performed March 24, 2014.

"We don't know how much this sets back his recovery at this time," A's trainer Nick Paparesta said Saturday night. "He's going to go home and we'll set him up to see a specialist."

Parker, acquired from Arizona before the 2012 season, was 12-8 in 2012 and 13-8 in 2013.