CARLTON midfielder Ed Curnow's chances of returning from a bruised larynx before the end of the season are fading, with a specialist ruling him out for another four rounds. 

Curnow has not played since suffering a knock to his throat in the Blues' round 14 loss to Richmond. 

Carlton was initially hopeful Curnow would miss no more than five weeks and return for Saturday night's clash against Geelong. 

But the leadership group member's recovery has been slower than expected and a specialist advised the Blues on Monday he would not be fit to play before round 23. 

Given the Blues are out of the finals race, Curnow's rehabilitation will have to proceed without any further hiccups for him to play again this year.

"Ed Curnow saw the specialist yesterday. (He's) still going to be out for four weeks which is disappointing and probably longer than we first thought," Carlton football manager Andrew McKay told carltonfc.com.au. 

"We're just going to have to play that one by ear." 

Carlton could, however, be bolstered against Geelong by the returns of defenders Caleb Marchbank, Simon White and Ciaran Byrne. 

Marchbank (shoulder) has been sidelined since round 15, while White (knee) and Byrne (groin) have missed two weeks and one week respectively. 

McKay said the three defenders would have to pass fitness tests at the end of the week to take on the Cats. 

"(Marchbank) has progressed really well the last two weeks. He was close last week without getting up," McKay said. 

"Simon White has recovered really well. (He) has progressed really quickly the past couple of weeks.

"I expect that (Byrne) will be available to play at some level." 

Key defender Alex Silvagni (knee) is expected to miss another four weeks, while Dylan Buckley (hamstring) is set to miss another two. 

First-year players Cam Polson (shoulder) and Patrick Kerr (hip) won't play again this season after undergoing surgery.