ADELAIDE defender Brent Reilly will remain in intensive care for days after having parts of his skull fractured into small pieces in a training accident.

Reilly is in a stable condition and "breathing by himself" on Tuesday, the day after emergency surgery, Adelaide's club doctor Andrew Potter says.

"I don't really want to go into it further other than that it was a fracture at the side of the skull and it involved more than a crack, it was just several small pieces, and that is why it needed to be established," Dr Potter told reporters on Tuesday.

"His condition at the moment is as expected. He is breathing spontaneously by himself, He is sedated which is normal standard procedure for this situation but he's breathing by himself.

"His condition hasn't deteriorated overnight. It has remained stable and he's communicated with his wife and family this morning and last night."

Reilly was kneed to the head during a match simulation drill at training on Monday.

Potter said it was too soon to say whether Reilly would play again.