Erat, acquired from the Nashville Predators along with Michael Latta for top prospect Filip Forsberg on Wednesday, was injured when he was hit into the boards by Florida defenseman Erik Gudbranson. After staying on the ice for a few minutes, Erat needed help to get to the dressing room and couldn't put weight on his right leg.
Gudbranson was assessed a five-minute penalty and a game misconduct on the play.
Erat was not on the Capitals' bench at the start of the second period. His return is questionable, according to a team spokesman.
I have been blessed to play for 16 years in the NHL; it has been an amazing ride. I would like to thank the Tampa Bay Lightning and New York Rangers organizations and owners for providing me the opportunity to play the sport I love for so many years. I could have never played for so long or accomplished all that I have without the unwavering love and support from my wife, Heather, our three sons, Ryan, Lucas, and Mason, and my parents.
— Martin St. Louis after announcing his retirement from the NHL on Thursday