ST KILDA captain Jarryn Geary has undergone surgery on a corked thigh and is expected to miss "a few weeks".

Geary experienced severe pain from bleeding in the muscle after the Saints' 40-point win over the Demons on Saturday night and was sent to hospital.

The injury occurred in the third term after Geary's goal-saving collision with Demon Jayden Hunt.

St Kilda captain Jarryn Geary underwent surgery overnight after receiving a corked thigh in this passage of play: https://t.co/6WDnI7q9fe pic.twitter.com/WA0MZ3fdEf — AFL.com.au (@AFLcomau) April 21, 2019

Coach Alan Richardson told Channel Nine that the skipper was likely to spend the next week in hospital.

"That was going to be a certain goal to the Demons and 'Gears' as we want to do, has left his man and just made body contact and so unfortunately he's ended up in hospital last night," Richardson said.

"(There was) a lot of pressure from the leg so they had to slice him open just to alleviate the pressure, so he's probably going to be in hospital for a week and he won't play for a while.

"That's Geary, he's an inspirational leader. His teammates love him, we all love him, he continues to put his body on the line for his footy club and his teammates. He's a ripper."

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Saints teammate Jack Sinclair told Channel Seven that Geary will be sidelined for several games.

"He's been battling that (corked thigh) for a few weeks now," Sinclair said.

"I think he got home after the game last night and it worsened a fair bit, so he went to hospital and had a little operation. He'll probably miss a few weeks."

Over the next month the Saints have a chance to consolidate their position at the top of the ladder when they host Adelaide at Marvel Stadium, take on Greater Western Sydney at UNSW Canberra Oval, host West Coast at Marvel Stadium and then face Collingwood at the MCG.