The actor was playing Buddy in ”Elf the Musical” at The Lowry in Manchester
The actor tweeted on Sunday saying: "In the matinee of Elf, there was an incident on stage and I broke my ankle.
"Still in hospital at the moment but all your tweets and messages are keeping my spirits high. Heartbroken to finish the Elf run early but you're in safe hands with this wonderful cast and my brilliant understudy, Colin."
— Ben Forster (@thebenforster) January 7, 2018
The theatre tweeted to say that the matinee had been stopped at that audience members would be offered a refund or seats for a future performance.
Unfortunately, today’s matinee show of @elfmusicaluk has had to stop. Patrons will be offered a full refund or seats for a future performance. Our apologies for any inconvenience caused.
— The Lowry (@The_Lowry) January 6, 2018
Based on the 2003 film starring Will Ferrell, Elf tells of an orphan who learns his real dad lives in New York and not the North Pole. It features a book by Thomas Meehan and Bob Martin, with music and lyrics by Matthew Sklar and Chad Beguelin.
Elf runs at The Lowry until 14 January.