Little has been playing through the pain barrier after sustaining the injury shortly after Christmas and a scan yesterday confirmed he requires treatment.
The 31-year-old does not how long he will be sidelined for but has not given up hope of returning before Reading's final game of the season at Blackburn on May 13.
"I've had it for a few months now, I've been getting through it but I can't do it any more," Little told the club's official website, www.readingfc.co.uk.
"I don't know how it first happened, it just started to come on not long after Christmas.
"At that point I could get through it, but I knew it was there. It became more and more of a struggle and has been getting to me.
"It's become a fight just to get out on the pitch, so I'm at the stage where I want to get it right because I can't keep going like this.
"It's getting difficult just to get into training in the morning. Before games I've been trying to get it going and work it, but it's really grinding me down.
"Right now I don't know how long I'll be out. I've not had this type of injury before.
"(Reading physio) Jon Fearn says I could be back this season if it settles well, but it might not settle and then I'd have to get it right for the summer.
"It's been hampering me and has been affecting what I do. I've got to drop out as there are others desperate to play.
"If we didn't have anyone it might be different but I can get it right now.
"I want to make sure it's right. If I can come back this season then great, but if not I'll have to take it on the chin and wait for next season."
Reading have received more positive news on Marcus Hahnemann, who withdrew from Sunday's 1-0 Barclays Premiership defeat by Tottenham at half time because of a hip injury.
A scan yesterday revealed only minor damage and the American keeper could return in time for Saturday's clash with Liverpool.
"It's a minor hip strain. A muscle in the hip has a very, very low grade strain," said Fearn.
"The scan gave us even better news than we anticipated. He has a very good chance for the weekend and we'll see how it responds."
Skipper Graeme Murty could also be available to face Rafael Benitez's side after missing the trip to White Hart Lane because of a calf problem.
"Graeme had a good jog on Tuesday and he's improving all the time," said Fearn.
PA Sport