The former Chelsea man, 25, suffered torn ankle ligaments in a 1-1 draw against Nuremberg at the weekend and had to be helped from the pitch after being treated for the problem.
The severity of the blow means he will now be sidelined for up to six weeks, having started 17 of the club's 18 league games this season.
It also seems likely that the news will prevent Hamburg from allowing another former Chelsea defender, Jeffrey Bruma, to leave the club on loan.
Coach Thorsten Fink said: "I told him he will be important for us and get his chance to shine."
- Sports & Recreation