The Spaniard ruptured his cruciate ligament in the Latics' game against Fulham, and will be unavailable for the rest of this term as he recovers from surgery on the knock
The Spaniard picked up the injury towards the end of the game at Craven Cottage and was stretchered off, with a scan revealing the extent of the damage.
Ramis has become an important part of Wigan’s defence since joining from Real Mallorca in the summer, making 19 appearances and scoring three goals.
Manager Roberto Martinez has said he is disappointed to lose the defender, but is confident his squad is strong enough to cope with the absence.
"Nothing can disguise the fact this is a massive blow because Ivan is a key member of the group," he told the club’s official website.
"But we're relieved it is not as severe as we feared it could have been."
Ramis will undergo surgery on his knee and will hope to recover in time for the new season, while Martinez will look to bring in cover for the Spaniard during the transfer window.
"The most important thing now is to think of Ivan's welfare, get the operation completed, and for him to begin his rehabilitation," he added.
"Ivan is a very strong and positive character and he is determined to return to fitness as soon as he can.
"He will receive the best possible medical rehabilitation as the club ensures to have him return as an even stronger footballer."