The news is not good for Wilson Ramos.
An MRI has revealed that Ramos has a torn ACL in his right knee, an injury which will likely sideline him for most, if not all, of this season.
Leon, who will wear No. 41, batted .319 with 10 doubles, one home run and 12 RBIs in 27 games this season with the Senators. He also has been strong behind the plate, throwing out 41 percent (12 of 29) of would-be basestealers in 2012 and 51 percent of runners attempting to steal in the last three seasons combined.
The 23-year-old Leon is considered an excellent defensive catcher - he was actually named the best defensive catcher in the Carolina League last season by Baseball America. He was able to make it to Cincinnati in time for today's game because the Senators were playing in Akron, Ohio, this weekend.
Leon is also a switch-hitter. He will be added to the Nats' 40-man roster, which only previously held 39 players.
Ramos has batted .265 with three home runs and 10 RBIs in 25 games with the Nats this season.