Ireland suffer 'big loss' as Porter ruled out of rest of Six Nations
Porter, 26, and fellow prop Tadhg Furlong have become mainstays of the starting XV under head coach Andy Farrell.
The 42-times capped Porter suffered the injury during Ireland's 57-6 thumping of Italy last Sunday.
"He (Porter) is a big loss," admitted Ireland's forwards coach Paul O'Connell at a press conference on Thursday.
"He is a modern prop forward, excellent scrummager but also his ball carrying for us, and he is a really good poacher.
"He is a great man to get penalties at the ruck, he is no nonsense to coach and gets on with it, he is very easy to work with. He will as I said be a big loss."
Porter will miss Ireland's tricky away match against England on March 12 and the final game at home to Scotland a week later.
Both Ireland and England have lost a game apiece but still entertain hopes of the title. They must hope Grand Slam-chasing France slip up against either the Welsh on March 11 or England in Paris on March 19.
O'Connell, though, believes Porter's potential replacements, the vastly experienced Cian Healy and David Kilcoyne, are capable of turning in big performances.
"These guys (Healy and Kilcoyne) have a lot more rugby under their belts than their match minutes for Ireland this season would have you believe," said O'Connell.
"He (Porter) is a loss but this is a great opportunity for the other two.
"Kilcoyne started against England 12 months ago but went off early to be replaced by Cian who put in a huge performance (in a 32-18 Ireland win).
"There is great experience there and both of them are really enthusiastic.
"I am very happy what we have behind Andrew Porter."