Gerard, 25, has made only four league appearances, all as a substitute, for the club this season because of the problem. His only full game was the UEFA Champions League Group F match against Celtic FC in Glasgow on 14 September.
Consultants declared the operation a complete success but the player will not be back in action for between six and eight weeks. Gerard is the sixth Barça player to have undergone surgery this season, the others being Henrik Larsson, Thiago Motta, Gabri García, Edmílson and Albert Jorquera.
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