“Incredibly disappointing to get a season-ending injury, as I was very excited about my first full season as a professional,” Pledger said.
“I guess I have learned early that part of being a professional rugby player is dealing with injury.
“My energy now will be put into rehabbing as best I can so I can come back in the best possible shape. I will be able to focus a bit more on my study too.”
Pledger was a surprise omission from the All Blacks XV squad last year, with coach Jamie Joseph opting to keep him at home to focus on his debut Super Rugby campaign.
Joseph is also head coach of the Highlanders.
Two-test All Black Folau Fakatava will likely assume the starting duties, with Adam Lennox serving as the backup, while Nic Shearer is part of the extended squad.
The Highlanders face the Crusaders on January 30 in Timaru in their opening pre-season clash before hosting the Super Rugby Pacific season opener, also against the defending champions on February 13.
Ben Francis is an Auckland-based reporter for the New Zealand Herald who covers breaking sports news.