Essien injury hits Chelsea sales plans

Chelsea may have to reassess their January transfer window policy after the early diagnosis on Michael Essien's knee injury at the Africa Cup of Nations suggested that the midfielder would be out for one month.

The club have said they will not be able to make a clear assessment until the player returns to their Cobham training ground at the end of the week from Angola. The Ghana team doctor said the player will be out for a month with a partially torn medial collateral ligament in his knee and damage to his meniscus, although Chelsea are yet to confirm that.

Chelsea have primarily considered strikers in the transfer window – Luis Suarez and Sergio Aguero among them – but they have also had a tentative bid for Everton's Jack Rodwell turned down. Replacing a player of Essien's qualities is quite another question. They have plenty of midfielders who can deputise in the holding role, but Essien is much more effective when unleashed in a more advanced position.

Chelsea will wait until the player returns for any big decisions but his injury is, sustained in a training session, means that he is more than likely to miss the Arsenal game on 7 February. The 27-year old flew out to Angola last week having recovered from a hamstring injury and played as a substitute against Ivory Coast. He is reported to be on crutches and will miss Ghana's game against Burkina Faso tonight.

The injury is also bound to reignite the debate over compensation for club sides when a player is injured on international duty which began when Robin van Persie was seriously injured playing for the Netherlands. It is thought that the Ghana football federation do not have a policy that covers their players' wages.

Anthony Annan, the Ghana midfielder, said: "Michael was turning to make a pass when he just went down. There was no contact from any other player but those around him say they heard a click, and then the physios rushed over."

Speaking on Friday night, before Essien suffered his injury, the Chelsea chairman, Bruce Buck, said that the club would consider buying this month to replace an injured player. Buck said: "We have only used the January transfer window a couple of times. You don't buy players just to buy players; you buy them to fill the need or because they are a better player than the one we have in a particular situation.

"A player really has to suit us for us to buy him, and then, even if a player is available, he has to be available at the right price."

He added, in an interview with Chelsea TV: "With regards to January, we asked for the transfer ban to be suspended as an option because several months ago we didn't know if we were going to have any injuries or great opportunities for us to buy a player."

Buck maintained that the club still believe that they will overturn Fifa's ruling over the Gaël Kakuta case that, if upheld by the Court of Arbitration for Sport, will mean a transfer ban until the summer of next year. That they turned down Aguero's wage demands of £140,000-a-week demonstrates that they are confident they will be in a position to buy players this summer.