The 32-year-old suffered a knee ligament injury in the 1-0 victory over Swansea and it was initially hoped he could be back before the summer.
But manager Billy Davies told the club's website: "He is finished. I don't think he will make the play-offs.
"We could have afforded to lose any player in the side this season - apart from McKenna."
Source: BBC Sport
Source: BBC Sport