Midfield player Garder had the operation on Tuesday after he sustained cartilage damage in Bolton's 3-2 defeat by Liverpool FC last Saturday.
'A huge loss'
The 23-year-old is likely to be out until November and manager Sam Allardyce said his absence was a "huge loss" to the Premiership side. "Unfortunately, he is going to be missing for four to six weeks," Allardyce told the club's official website.
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