Marco van Ginkel successfully underwent knee surgery Thursday, but Chelsea confirmed their new midfielder will be out for approximately six months.
Source: Chelsea's Van Ginkel out for six months (http://www.fifa.com/worldfootball/clubfootball/news/newsid=2181663.html?cid=rssfeed&att=)
I don't really feel this would affect them in any way because they have a strong squad already. So he should just get well soon