Nylander was hurt when defenceman Nolan Yonkman crashed into him behind the net during a drill.
The 31-year-old Nylander played in 71 games last season for Washington, scoring 17 goals and assisting on 39 others.
Entering his 11th year in the NHL, Nylander has also spent time with the Chicago Blackhawks, Tampa Bay Lightning, Calgary Flames and the Hartford Whalers.
He was originally selected by the Whalers in the third round (59th overall) of the 1991 NHL entry draft.
with files from Sports Network
