The news comes less than a week after Kearney was named in the wider Leinster squad to face the Scarlets - a move that heightened hopes that the problem was close to being resolved.
Kearney suffered the initial setback against Connacht on September 28 in what was his first game back since Ireland's summer tour of New Zealand and he has since missed Leinster's PRO12 derby with Munster and their two opening Heineken Cup wins.
The fresh diagnosis means the 26-year-old is unlikely to play again in 2012, with the league encounter with Edinburgh at Murrayfield on January 4 a possible return date.
That would leave Kearney with just two further Heineken Cup games to prove his fitness ahead of Ireland's Six Nations opener with Wales in Cardiff on February 2.
His absence is a huge blow to Ireland coach Declan Kidney, especially as Kearney has worn his country's No15 shirt in each of their last 12 Tests dating back to the World Cup win over Australia.
Kidney's options appear a little more limited than he would like when it comes to replacing the European Player of the Year, with veteran Geordan Murphy having retired from international rugby, Connacht captain Gavin Duffy out injured and Felix Jones only having returned to action last weekend following a lengthy absence.
Fly-half converts Ian Keatley and Ian Madigan are possible options having being employed at full back for Munster and Leinster respectively but the form of Denis Hurley and the international experience of the versatile Keith Earls could see Kidney turn to either of them for the opening autumn international against the Boks on November 10.