The club says the 21-year-old Cowen is expected to make a full recovery from Saturday's operation in New York.
Cowen, the No. 9 overall pick in the 2009 NHL Draft, played in all 82 games last season as a rookie, scoring five goals and adding 12 assists with a minus-4 rating. He also was in the lineup for Ottawa's entire seven-game, first-round playoff matchup against the New York Rangers. Cowen had one assist and four penalty minutes in the series loss.
In three games this season for Binghamton of the AHL, while the NHL was shut down because of a lockout, Cowen had three assists.