Essien, 27, sustained the injury in training while on international duty at the tournament in Angola.

The Ghana player arrived back at the club's Cobham training ground this week and Chelsea's medical staff carried out an examination of the affected knee.

Essien's injury came as a blow to Ghana who were hoping he would recover from the injury to play some part in their vital group clash with Burkina Faso.

They managed to win that match 1-0 to reach the quarter-finals, however Essien's absence weakens them for the knock-out stages.

Essien stands to miss matches including Chelsea's Barclays Premier League clash against title rivals Arsenal at Stamford Bridge and the opening leg of their Champions League tie against Jose Mourinho's Inter Milan.