The team won't know the exact extent of the injury until Sunday, but with Ramos likely headed for the disabled list, Johnson said Jhonatan Solano would be first in line to replace Ramos on the roster. Kurt Suzuki, who has been alternating starts with Ramos, would take over as the regular catcher.
"It's something you can't rush back," Johnson said. "You don't want to be short in that department."
The 25-year-old Ramos saw his 2012 season end on May 12, when he suffered a serious knee injury. He came back strong this year, and is hitting .300 with two home runs and a .991 OPS in 23 plate appearances.
Ramos suffered the injury after hitting a line drive back at O'Flaherty, which deflected to second baseman Dan Uggla for a 1-4-3 putout.
"It's tough. Wilson's worked so hard to get back where he's at now," third baseman Ryan Zimmerman said. "He's obviously a big part of this team, but we have a guy like Kurt there, who's capable of catching every day. If that's the case, Kurt will step in and play more than he has.
"That's one good thing about this team, we have so much depth. Something like that, which really would hurt another team, we can kind of handle. But hopefully it's not as bad as they think, and he'll be back soon."
The Nationals acquired Suzuki last August to help plug the hole left by Ramos' injury, and now he's in that position once again.
"You never want to see anybody get hurt," said Suzuki, who is 3-for-13 with a home run this season. "To see how hard he worked and see how hard he worked out to get himself back to this point, to see a freak accident like this happen, it [stinks]. It's a big blow, with how good he is. It's tough to swallow."
Solano played 12 games for the Nationals last season, between late May and the middle of July, and went 11-for-35 (.314) with two home runs. Through his first four games at Triple-A Syracuse this season, he was 3-for-18 (.167).