The Schalke forward has revealed his sadness that he will be forced to miss his side's coming matches, including the Champions League tie with Galatasaray
The Dutchman was stretchered off during Saturday's 2-1 derby win over Borussia Dortmund, and will be forced to sit out his side's Champions League last-16 clash with Galatasaray, which would have seen him face international team-mate Wesley Sneijder.
"I knew immediately that something was wrong," the 29-year old told De Telegraaf.
"I hate that I'll spend weeks in the stands but it could have been even worse. It's annoying that I have to watch instead of playing against Wesley.
"Now I will watch it with my father and brothers at the stadium. That will be painful, I think."
Schalke and Galatasaray kick off at 20:45CET on Tuesday, having drawn the first leg 1-1 in Istanbul.