The 31-year-old veteran left-winger has suffered four concussions in the last 19 months and hasn’t played this season.
Senators GM Pierre Dorion told reporters this morning that MacArthur will sit out the remainder of the year on doctor’s orders.
MacArthur missed all but four games last season due to a concussion. He was hit in an intra-squad scrimmage during training camp last fall and hasn’t played since.
MacArthur signed a five-year contract extension worth US$23.25 million in 2014.
Dorion said Friday that MacArthur is "devastated" by the news.
"He says he has felt great for a long time," said Dorion. "This came to us as a bit of a shock."
But MacArthur’s health is the team’s priority, Dorion added.
"When numerous doctors indicate to us that he should not play hockey this year, we’re just going to follow that."
With MacArthur out, Dorion said he’ll look for some help at forward but acknowledged prices are high right now.
"We feel comfortable with what we have here and we’re prepared to give up something to get something but you can’t get top-end players for seventh-round picks," he said. "But if we don’t do anything, I like the team we have."
The Senators are second in the Atlantic Division with a 24-15-4 record. They face the Toronto Maple Leafs on Saturday night.
Dorion also said goalie Craig Anderson could be back by the end of the month or in early February. He’s been on personal leave since December while his wife was undergoing cancer treatment.
"Once he’s back, he’s back for good," Dorion said.