Swansea goalkeeper Michel Vorm to have operation in January Swansea goalkeeper Michel Vorm will be sidelined for four weeks when he has a knee operation in January. The Netherlands international has confirmed he will have surgery on a cartilage problem. Vorm, 30, will have the operation in a bid to make sure he is fit for the World Cup finals in Brazil in June 2014. "I have to do it now before the World Cup and we don't have too many league games in January," said Vorm. We will try to manage it for a month and then at the beginning of January I will have an operation Michel Vorm Swansea City The goalkeeper travelled with the squad for Thursday's Europa League game against St Gallen despite missing Monday's home draw against Hull City. Gerhard Tremmel started in goal against Hull on Monday with 18-year-old Slovenian Gregor Zabret on the bench. Vorm, who has had two operations on his right knee, has been dogged with a cartilage problem in his left knee recently. "I have had some problems with my left knee for a while," said Vorm. It keeps swelling up, I have had some problems with it in the last few weeks and we have tried to manage it. I can play but I need a bit longer to make sure I am fit for the next game. It was OK, but then it got worse and worse. Vorm says he had hoped to avoid having an operation until after the World Cup. "I had a scan on Monday and we knew there was a tear, but it is a bit bigger now and we have to do something about it," said Vorm. We will try to manage it for a month and then at the beginning of January I will have an operation. Then I will be out four weeks. This month we have five or six games until the beginning of January. I just hope my knee settles down and I have to say it's OK now. Maybe I can play a few games, but I need to get it done, especially with the World Cup coming. After the first scan, the doctor said I could have an operation after the World Cup. But he said if it gets worse, you need to do something about it. It has got worse, so we need to do it.