Michael Laudrup had hoped his goalkeeper would be able to fight through until the New Year but an operation is urgently required and the date of his return is not yet known
Manager Michael Laudrup had hoped that the Netherlands international would be able to get through the hectic fixture schedule at the end of December before going under the knife, but he sustained further damage in last Sunday's 1-1 draw at Norwich City.
Vorm played the whole game at Carrow Road, but he is now unlikely to feature until well into next month, with Gerhard Tremmel expected to take his place between the posts.
A statement on Swansea's official website confirmed that 30-year-old Vorm will be unavailable in the near future, but did not put a specific timeframe on his expected return.
It read: "Surgeons will explore the knee before carrying out work on clearing any loose ligaments and fragments of bone, and a diagnosis on the length of time he will be sidelined depends on the scale of the operation."
The Netherlands international has made 13 appearances in the Premier League this season, keeping five clean sheets.