Chelsea's Ghanaian midfielder Michael Essien yesterday underwent a successful knee surgery in France to repair a ruptured anterior cruciate ligament.The midfielder suffered the injury during Ghana's World Cup qualifier against Libya on September 5.The 25-year-old had to wait two weeks for the swelling to go down before being operated on in Lyon.Essien is expected to be out of action for five months and a Chelsea spokesman told BBC Sport: "The operation has been a success."He has been a regular for Chelsea since his ₤24m move from Lyon in 2005, scoring 14 goals in 132 appearances.Essien landed awkwardly during the qualifier against Libya and was taken to hospital for scans, which confirmed the ligament damage.Meanwhile, Chelsea manager Luiz Filipe Scolari is still shopping around in search of a replacement to cover for the loss of the injured influential Ghanaian midfielder.Scolari told BBC London 94.9: "I have some ideas about this position. I spoke to Peter Kenyon."He's trying to move something today, tomorrow or maybe next week."Frank Lampard and defender Ricardo Carvalho admit the loss of Essien to a cruciate ligament injury will have a big impact on the team."Everyone will miss Essien, he's an important player for us and now we have to be with him and give him our comfort," Carvalho said."We'll try to help him because it's a difficult time for him."Source: BBC