Lynch joined the Bulls from Castleford in 2004
Bradford Bulls will be without captain Andy Lynch for the next four Super League games after being told he needs knee surgery.
The 30-year-old prop has been struggling with damaged cartilage and is set to undergo surgery to correct the problem on Tuesday.
"It's a measure of Andy's stature that he has played through the pain barrier," coach Steve McNamara said.
"He has never given less than 100% in all the games he's played."
McNamara added: "The time has now come for him to have the operation with a view to being fully fit for the business end of the season."
The Bulls are also waiting to find out the extent of the knee injury to back row forward James Donaldson.
Donaldson was stretchered off the field during the Challenge Cup quarter-final defeat by Warrington.