Anthony Gardner will be sidelined for up to five months after learning that he will require surgery to repair his injured Achilles.
The centre-half, who suffered the injury at the end of last month, will travel to London later this week to undergo the operation.
"Anthony will see a specialist in London and have an operation on the Achilles," manager Dave Jones told the club's official website.
"It's a blow to the boy and the team because he was playing very well and had a good start to the season.
"We wish him all the very best in his recovery and look forward to welcoming him back as soon as possible."
Gardner joined Wednesday on a free transfer in 2012.