FORMER Sydney defender Alex Johnson believes he can be back playing footy by the early rounds of next season if a club gives him another shot in the AFL.

Johnson, who underwent a reconstruction on his right knee after rupturing his ACL against Melbourne at the MCG in August, was delisted by the Swans last week.

The surgery was the 26-year-old's sixth ACL operation after he'd had his left knee repaired five times since first going down during the pre-season of 2013, just months after helping the Swans win a premiership.

Sydney couldn't find a place on its list for Johnson but did offer him an off-field role with the club for next year, which he refused in order to try his luck should another club give him a shot.

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Johnson told SEN on Thursday that his surgeon Julian Feller told him there was no reason he couldn't do the appropriate rehabilitation and be fit to play early in 2019.

Feller performed ACL surgery on Collingwood defender Tyson Goldsack, who is back playing for the Pies after tearing his ACL in this season's JLT Community Series.

"Julian did exactly the same operation on Tyson at the start of this year and as we have seen, he has played the last couple games and is playing in a preliminary final this week," Johnson said.

"I've had the same thing done and I back myself to get back and contribute for the majority of 2019.

"I've got a really good relationship with Julian, he's done the last couple of ACL reconstructions on me.

"He is really honest with me and he said, 'what do you want to do?'

"I said I would love to continue playing footy.

"He said the way this one happened, it is just pure bad luck and you look at what happened with your left knee, that's as strong as anything now, you don't have to worry about that anymore.

"There is no science behind it, but it is reasonably common for people to do the other knee if they've already done one.

"He said now that both are reconstructed, you won't favour either, you'll be strong in both, you'll rehab both and I back you to get back and play."

Johnson was the feel-good story of the season when he played against Collingwood in round 20 this year, his first senior game since the Swans' 2012 flag win over Hawthorn.

The luckless defender played a key role in the home side's win, but his season was over a week later when his right knee buckled in the opening quarter against the Demons.