Earnie left training with Norwich last week on crutches and his boss, Peter Grant, is fearing the worst.
"To be fair he was in a lot of pain the other day there and I am not expecting the best news to be honest," said Grant.
"I have myself ready for that after seeing the way he went down. Sometimes you need surgery to make sure it is okay, sometimes you need surgery if it's major.
"Groins are very, very difficult to judge, but the way he fell I was fearing the worst."
Earnie has been a target for Premiership clubs this January but now that's gone out of the window.
Toshack might also be with central defenders Jams Collins and Danny Gabbidon for the trip to Belfast next month. Both were injured during West Ham's draw with Fulham on the weekend.