Contreras was injured Friday. An MRI scan Saturday showed he tore his ulnar collateral ligament and flexor pronator tendon.
The 40-year-old Contreras had right elbow surgery last year. He reinjured the elbow in the seventh inning Friday night while facing Miami's Omar Infante.
After throwing his fifth pitch of the inning - an 89 mph fastball - Contreras grabbed his right arm and staggered to the ground on the grass between first and second before leaving the game.
Conteras was 1-0 with a 5.27 ERA in 17 games this season.
Michael Schwimmer has been recalled from Triple-A Lehigh Valley to take Contreras' spot.
