"At this point, we don't know if it is surgical or non-surgical," Yost said.
Strahm, who went on the disabled list Saturday, pitched in the first game of Saturday's doubleheader with the Twins, but he was removed with two outs in the fourth when he hit a batter and walked two others. Strahm said he felt something wrong after he jumped for a chopper over his head off the bat of Miguel Sano earlier that inning.
"I felt it really bad on that chopper over my head," Strahm said. "I jumped up and felt it, and then I couldn't power off it."
Strahm was walking around the clubhouse Sunday morning without a pronounced limp.
"I'm just trying to manage the pain right now," Strahm said.
Strahm, 2-5 with a 5.45 ERA, said he has dealt with tendinitis in that knee for quite some time.
"I get it on and off," Strahm said. "Something I dealt with this spring, and it flared up again."