King has had chronic injury problems throughout his career and has made just four league appearances this season, but he had been on course for a return to the first team after taking part in a series of Spurs training sessions.
However, on Wednesday Redknapp revealed the England defender had pulled up with the final kick of the ball, and now has no idea when King will return as he heads for further surgery.
"When you have a problem like that, you tend to pick up other injuries when you don't train regularly," Redknapp said.
"He had a groin problem, which we waited and waited and waited to see if he'd need an operation or not, but he trained and was getting through the sessions okay, and then in the last minute the other day he struck a ball and felt that he had torn it right away from the bone.
"They (the medical staff) say it could be a good thing. It could be better to have an operation to sort it out, but now we're back to long recovery sessions for him.
"How long it's going to be? I don't know."