Essien ruled out of World Cup
"An evaluation by a combined team of medical experts from the Ghana Football Association and Chelsea Football Club revealed that Essien will not make (a) full recovery until the end of July," Ghana's FA said on its website.
The Chelsea midfielder has been recovering from a knee injury picked up at the African Nations Cup in January. He played just 45 minutes at the tournament in Angola after suffering a hamstring injury in the Champions League in November.
His loss is a blow to Ghana whose coach Milovan Rajevac last week described Essien as the leader and engine room of his team. Rajevac is due to decide on his final 23-man squad on Tuesday.
Ghana open their World Cup campaign against Serbia on June 13 and also play Germany and Australia in Group D.
Essien is hugely popular in Ghana and his image is pasted up all over the country.
He has scored seven times in 50 appearances for his country and played at the 2006 World Cup in Germany.
Essien hinted several weeks ago he might not be fit for the tournament in South Africa, which kicks off on June 11.
"The last thing I want is to rush back and cause more problems down the line. If I make it for the World Cup then great - if not, I have my whole career ahead of me," he told the Chelsea website.
Ghana are still unsure of the fitness of two other key players, Stephen Appiah and John Mensah.