I probably could get through games - but not at the level I want to be at GB captain Paul Sculthorpe

The Great Britain captain will have a cortisone injection this week which means he should be able to finish the rest of the campaign with St Helens.

"It's a big honour playing for your country but it's something you've got to be fully fit for," said Sculthorpe.

"The good thing is the injury's nothing long-term - it can be fixed."

Interview: St Helens and GB captain Paul Sculthorpe

Great Britain coach Brian Noble is expected to turn to vice-captain Jamie Peacock to replace Sculthorpe.

The Leeds forward took over in last year's Tri-Nations and took over the captaincy when Sculthorpe came off during the June Test against New Zealand.

On Saturday, Saints made mathematically sure of finishing top of Super League and Sculthorpe hopes to help them go on to win the Grand Final at Old Trafford.

"I want to be part of this great Saints side this year," Sculthorpe told BBC Radio Five Live.

Sculthorpe succeeded Andy Farrell as Great Britain captain in May 2005 but missed that year's Tri-Nations after undergoing major surgery.

The 28-year-old admitted he was disappointed to be missing out on the Tri-Nations again but said he had to think about his future

"You've got to think long term and you've got to think after rugby as well," he said.

"I went to see the surgeon in London and he said 'there are guys with a lot worse knees still playing who have had nothing done'.

Hopefully the operation can rid me of all the injuries I've had because they've all been related to this knee Paul Sculthorpe

"I probably could get through games - but not at the level I want to be at, and which people are used to seeing me at.

"I want to be at the top of the game and not limping through games."

He has only led the Lions out once since taking the captaincy, and had to come off early in that 46-14 win over New Zealand with an injury to his left knee

But Sculthorpe vowed he would return for Britain in the future.

"It would have been easier for me to go on tour, limp through training, limp through games, say I've captained my country and not do either myself of the team any favours.

"I'm not willing to do that and I'm looking long term.

"I've had two really frustrating years these past two years with this injury.

"Hopefully the operation can rid me of all the injuries I've had because they've all been related to this knee."

Sculthorpe, a two-time Man of Steel, only featured in 16 games last season because of persistent hamstring and back injuries and the operation on his knee problem.

The Tri-Nations tournament - which this year is being held in Australia and New Zealand - gets underway on 14 October, with Britain's first Test on 28 October against the Kiwis.