CARLTON forward Charlie Curnow's horror injury run has deepened with the excitement machine to undergo surgery to repair another knee setback. 

Curnow suffered a fractured kneecap while completing his rehabilitation on the same knee that has haunted him for more than two seasons.

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He will undergo surgery on Wednesday. 

While the club was unable to put a timeframe on his return on Tuesday night, they suggested last year an injury of a similar nature would take at least 3-4 months to recover. 

They are expected to be extra-cautious given Curnow's history.

It will throw his pre-season plans into chaos for a second consecutive season after three separate setbacks ruled him out for the entire 2020 campaign.  

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The Blues had held high hopes for Curnow to bounce back strongly in 2021 after impressing at training in the latter stages of the Queensland hub in September. 

The 23-year-old failed to play a game this year after being put on ice in April.  

After missing the back half of the 2019 season with a medial complaint, Curnow dislocated his knee while playing basketball with teammates Patrick Cripps and Zac Fisher in a social setting in October last year. 

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He then fractured his kneecap in November before scans in April revealed he had suffered a hairline stress response while completing his recovery. 

Blues co-captain Patrick Cripps is also recovering from shoulder surgery that is expected to delay his return to contact training in January.