Kearney damaged cruciate knee ligaments in a game against Grimsby Town on 24th August and requires a knee construction operation which will take place on October 3rd, just before his 21st birthday.
The operation will rule out the highly-rated midfielder until next season.
But, team-mate Gary Walsh faces another wait before finding out the extent of the problem in his left knee. He is due to go back to the surgeon for further tests.
City physio Steve Redmond said: "Gary's feeling a little bit better and the scans have not shown any deterioration from how it was before. The surgeon wants him to spend the next seven to ten days doing some rehab work before having another look to see whether anything needs to be done."