The Republic of Ireland youngster, who was scheduled to remain on loan with the Foxes until the end of the season, has had a successful operation and will now head back to Manchester.
Cunningham left the Championship side on a high note as they won at Hull and with praise ringing in his ears from manager Sven-Goran Eriksson.
“He has been brilliant for us and one of our best players all season. He is very brave, has a good left foot and is a good player,” said the former Blues boss.
“He will be away for at least four months. It is really bad luck.
“We don’t know if we will have him back before the end of the season and I don’t think anyone could say about that at this stage.”
Sven told local reporters that he would like to sign Cunningham on a permanent basis but the left-back only signed a new four-year deal at CoMs last August.
The defender had been in and around the senior squad since January and sufficiently impressed Roberto Mancini to earn a lengthy new deal. The Galway-born 19-year-old played in several of City’s pre-season friendlies as well as adding to his international caps.
