GEELONG ruckman Dawson Simpson may not play finals, the club's medical staff fears. 

Simpson has had scans on his left knee, which he injured during the Cats' win over St Kilda on Saturday night.

While the club's medical staff are yet to complete their analysis of the scans, Geelong physio Mike Snelling was far from confident.  

"He obviously landed on that left knee and it buckled inwards, and he has actually sprained the (medial) ligament on the inside of his knee," Snelling told CatsTV on Monday. 

"Also, at the same time, his kneecap appeared to dislocate. It popped out to the side and then it popped back in.

"We're very happy that he doesn't have any cruciate ligament damage, or it appears so. 

"But his medial ligament is a fairly significant injury on its own, so he'll definitely miss a few weeks, and it might be tough for him to come back into the finals series."

There is a far brighter prognosis for another of the Cats' big men, with Hamish McIntosh, who has not played a game since crossing from North Melbourne last year, back on his feet after recent ankle surgery.

"Hamish has progressed well," Snelling said. "He had an arthroscopy on his ankle, and he's now running out on the ground.

"We expect him to progress his running over the next couple of weeks and then be integrated into training.

"So hopefully we see him before the season finishes."

Allen Christensen looks set to return for Friday night's clash with North Melbourne at Etihad Stadium after finally shaking off the hamstring soreness that has dogged him for the best part of a month.

"He had a good session on the weekend. He ran around well today," Snelling explained.

"We'd expect him to be into training and figure through everything there, then we'll test him for the weekend.

The Cats are also preparing to roll the dice and send veteran midfielder Paul Chapman into action in the VFL this weekend.

Chapman has been sidelined by soreness in both his hamstrings and has played since round four.

"He trained last week and trained at speed and got through the session really, really well," Snelling said.

"He's got to get through a couple more training sessions. We're always nervous, given the length of time that he's been out, but hopefully he gets through all of those sessions and we see him back playing on the weekend."