( CNN ) -- Chelsea midfielder Michael Essien will be out of action until 2012 after undergoing surgery on his right knee . The 28-year-old Ghana international damaged ligaments in his right knee during training last week , the third serious knee injury of his professional career . The English Premier League side confirmed the news in a statement on their official website . Villas-Boas confirmed as new Chelsea manager . `` Following an injury to his right knee in training last week , Michael Essien has had surgery to repair a ruptured anterior cruciate ligament and meniscus . '' The statement continued : `` The surgery was successful and Michael 's full recovery could take up to six months . '' Meanwhile , New Chelsea manager Andre Villas-Boas added : `` Everyone at Chelsea wishes Michael well for his recovery . `` His teammates and all the staff and I look forward to helping him return to playing as soon as possible . '' Essien 's injury could see Chelsea enter the transfer market for a replacement , with Tottenham 's Luka Modric and Porto 's Joao Moutinho both being heavily linked with a move to Stamford Bridge .
Joao Moutinho is ruled out for last week after undergoing knee surgery . The Michael Essien and Ghana midfielder injured himself in training last week . Chelsea have been heavily linked with Joao Moutinho and Chelsea .