Swiss forward Bunjaku out for six months
The 26-year-old underwent an operation for a torn meniscus in his right knee in Germany and was also found to have cartilage damage, the federation said on its website.
A late developer, Kosovo-born Bunjaku spent three seasons with lower division Rot-Weiss Erfurt before bursting on to the Bundesliga scene when he scored 12 goals for Nuremberg last season.
He made his international debut against Norway last November and was a member of Switzerland's World Cup squad.
Nuremberg said Bunjaku had complained of pain in his knee after Saturday's 1-1 draw with Hamburg SV.