"He'll be a while," New York coach Doug Weight said. "It hit him in the wrong spot. Some of those are a little shorter than longer. You could have a lot worse. You don't want to see guys get hurt, but hopefully he's back soon."
Mayfield has 12 points (two goals, 10 assists) and averages 18:06 of ice time in 48 games.
The Islanders already are thin at defenseman because of injuries to Johnny Boychuk (lower body) and Calvin de Haan (upper body).
De Haan, who last played Dec. 16, has missed 21 games is out indefinitely. Boychuk last played Dec. 27 but participated in the morning skate Monday and practiced Wednesday. Dennis Seidenberg was a healthy scratch Monday.
"We have bodies and that stuff will work itself out. You definitely have to put some added angst into some guys and challenge them, but just have to go play," Weight said. "We have a lot of good players, let's go to work."
The Islanders (26-22-6) play the Buffalo Sabres at KeyBank Center on Thursday (7 p.m. ET; TVA Sports, MSG-B, MSG+ 2, NHL.TV) and play the Detroit Red Wings at Barclays Center on Friday. They are even in points with the Columbus Blue Jackets for the second wild card into the Stanley Cup Playoffs from the Eastern Conference but have played one more game.