"Alexis Sanchez went to Barcelona this morning for a consultation with Professor Ramon Cugat," according to the team's statement. "The visit confirmed the diagnosis of the Nerazzurri medical staff, so it was decided to proceed with left ankle surgery.
"The plastic surgery of the peroneal tendons was then performed in the afternoon and was perfectly successful."
The 30-year-old is expected to be sidelined for the rest of 2019, as James Ducker of The Telegraph reports that Sanchez will be out of action for up to three months.
He's made just four appearances for Inter since joining the Serie A club on loan from Manchester United in the summer.
Sanchez scored twice during his full debut but was sent off after picking up two yellow cards.