Manager Bob Melvin said Tuesday he did not expect Trivino to be available in the postseason should the A's secure a spot after the 27-year-old right-hander was injured in his Bay Area apartment last week.
"We're saying, for sure, the regular season," Melvin said. "He's going to get a second opinion, I think, at some point in time here, but it doesn't look great, unfortunately."
Oakland will also be without right-hander Blake Treinen for the rest of the season because of a hip and back injury.
Trivino and Treinen were two of Oakland's most effective pitchers coming out of the bullpen in 2018 but had not been nearly as productive this season. Trivino was 4-6 with a 5.25 ERA in 61 games this season after posting a 2.92 ERA as a rookie. Treinen was 6-5 with a 4.91 ERA in 57 games after he had a 0.78 ERA as an All-Star last season.