Hull skipper Ashbee sidelined for nine months
Midfielder Ashbee ruptured his posterior cruciate ligament against Aston Villa in May but had been hoping to return next month, the club said on its website.
"Ian has had a setback with regards to his long-term problem and it's been four years since he had an operation on his knee," manager Phil Brown said, confirming that Ashbee would have surgery in Colorado next Monday.
"This is a big blow for Ian and a big blow for the club. Hopefully the scenario will be rehabilitation and Ian will be back in eight or nine months."
Hull, who lost their opening match of the season at Chelsea on Saturday, host Tottenham Hotspur on Wednesday.