The Flyers acquired MacDonald on March 4 from the New York Islanders in exchange for two draft picks.
Since joining Philadelphia, MacDonald registered four assists in 19 games and recorded over 20 minutes of ice-time in 14 of those games, including a Flyers-high of 28:49 at Pittsburgh on Apr. 12.
MacDonald, 27, led all NHL players in blocked shots this season with 242 and was one of three players in the NHL with over 200 blocks.
In 82 games with the Islanders and Flyers this season, MacDonald tallied four goals and 24 assists for 28 points.
The native of Judique, Nova Scotia, has played in 314 career NHL regular-season games with the Islanders and Flyers and has accumulated 17 goals and 76 assists for 93 points.
He was originally drafted by the Islanders in the sixth-round (160th overall) of the 2006 NHL Entry Draft.