The anterior cruciate ligament injury will keep Milito out for at least the season, however after surgery he is expected to recover fully.
"Milito underwent a successful knee operation this afternoon," a club statement read. "The Nerazzurri striker went under the knife after damaging his anterior cruciate ligament and lateral collateral ligament.
"The surgery was carried out at Pavia's Policlinico San Matteo under the supervision of FC Internazionale chief of medical staff professor Franco Combi."
Inter are fifth in Serie A.