Joleon Lescott ruled out for up to two months
The 27-year-old went under the knife to remove floating bone in the joint on the eve of the Premier League defeat to Tottenham at White Hart Lane. It means Hughes is in the market for a centre-back when the transfer window opens next month.
"We've lost Joleon for six to eight weeks," Hughes said. "That is a big loss to us and comes on the back of losing Kolo Toure for the African Nations Cup, so it doesn't leave much thinking about in terms of what we probably need in January."
Lescott is expected be ruled out of at least the Carling Cup semi-final against rivals Manchester United. It would also mean he will need to build up his match fitness for an England friendly in March ahead of the World Cup in the summer.