Ramos left Saturday's 3-1 loss against the Atlanta Braves when he tried to leg out a ground ball in the bottom of the eight inning.
Nationals manager Davey Johnson said Ramos will be re-evaluated Sunday and will almost certainly land on the disabled list.
Ramos is hitting .300 (6-for-20) with two homers and three RBI in six games this season. Kurt Suzuki should get most of the playing time until Ramos returns to action and Jhonatan Solano is expected to be called up from Triple-A Syracuse to take Ramos' place on the roster.
From the Washington Times:
The injury was quite a tough blow for the Nationals, as well as Ramos, after he’d worked incredibly hard to return from a torn anterior cruciate ligament and meniscus in his right knee suffered last May. In the process of rehabbing his injury, Ramos remade his body and improved his abilities behind the plate. He slimmed down, made himself leaner, along with more athletic and agile, and had easily been the Nationals’ most heart-warming storyline this season.