THE 2019 campaign of Collingwood defender Tom Langdon is almost certainly over after undergoing knee surgery.

The 25-year-old has been sidelined for nine games since injuring his right knee during the first quarter of the round nine win over St Kilda at the MCG.

Just a fortnight ago, Magpies coach Nathan Buckley reported Langdon was making progress towards a late-season return after several "encouraging" weeks.

However, Langdon went under the knife on Thursday.

The intercepting backman has previously experienced problems with the same knee.

"Unfortunately, it is almost certainly the case that Tom won't return this season," Collingwood football chief Geoff Walsh said.

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"At various times there was hope that he could avoid surgery, recover and get back late in the season but in the end it wasn't to be.

"Tom will have a few days or so away from the club, off his legs, and then commence his rehabilitation."

Langdon, who has played 89 AFL games since making his debut in 2014, last year stepped up to play as a key defender when the Pies were hit by injuries.

His efforts in the second half of the year and in particular in the five-point Grand Final loss to West Coast were admirable considering he conceded considerable size to his opponents.

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In the off-season he rejected approaches from Sydney and Fremantle to sign a new three-year deal with Collingwood.

In other injury news for the Pies, small forward Jamie Elliott (soreness) and runner Chris Mayne (knee) will undergo fitness tests, while defenders James Aish (shoulder), Levi Greenwood (hamstring), Darcy Moore (hamstring) and John Noble (calf) are among those unavailable for the big clash with Richmond at the MCG on Friday night.