Bad luck for West Ham loanee.
Henry is currently on loan at Danish side AC Horsens, but will return to London for treatment.
West Ham's Doneil Henry and Charlton's Karlan Ahearne-Grant
The 23-year-old was injured in the weekend game against SønderjyskE, going off after just seven minutes.
He spent last season on loan at Blackburn Rovers, and was establishing himself as a regular for Danish Superliga team Horsens this campaign.
Blackburn Rovers' Doneil Henry warms up
The injury is a bitter blow, and manager Bo Henriksen has expressed his disappointment, while also sending an uplifting message regarding Henry's future.
He said: "We are very sorry to lose Doneil Henry, who is both a very talented footballer and a great human being.
"He has a huge potential and insane skills and I have absolutely no doubt that he gets what he wants, because he has all the prerequisites to achieve it. We wish him the best of luck."
Werder Bremen's Ousman Manneh in action with West Ham's Doneil Henry
Henry had been scheduled to return to West Ham in the New Year, with his loan deal only until the end of 2016.
He now faces a battle to regain full fitness in time for the 2017/18 season.