The former Arsenal captain was signed this summer, but is yet to make his debut. He's under contract until June 2019.
"The operation was performed in Finland by Dr Sakari Orava and the recovery period is estimated at approximately four months," said Barca in a statement.
The Finnish medic, Doctor Orava, who operated on Vermaelen is the same specialist who operated on Pep Guardiola, sixteen years ago for a chronic hamstring condition.
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