Coach Jack Capuano provided the update before Saturday's game without saying what the injury was. De Haan did not return after being hit by Troy Brouwer in the third period of New York's 5-1 loss Thursday.
The Islanders trail the first-round series 3-2 and are already without two other defencemen. Travis Hamonic has not played since the next-to-last game of the regular season. Lubomir Visnovsky sustained a head injury in Game 4 on Tuesday.
Introducing the new official NHL App, available for iPhone, iPad and Android smartphones and tablets. A host of new features and improved functionality are available across all platforms, including a redesigned league-wide scoreboard, expanded news coverage, searchable video highlights, individual team experiences* and more. The new NHL App on your tablet also introduces new offerings such as 60fps video, Multitasking** and Picture-in-Picture.
*Available only for smartphones
** Available only for suported iPads