The Argentine has had his torn Achilles tendon operated on this week.
"The tear in the Achilles tendon has been repaired, reinserting another tendon from his leg," explained Doctor Francesco Benazzo at the clinic in Pavia.
"The operation lasted for 60-75 minutes, it all went perfectly. I just spoke to his wife now and we all know he is an important player for people all over the world.
"Now Javier will spend three weeks with his foot immobilised, then a second phase in which he will start walking. We expect a period of six months for a full recovery, as shown by recent examples.
"He will certainly play again. He proved his physique is in great shape, even at his age. There is the risk of losing muscular strength due to the period of immobilisation, but the Inter medical staff have been able to get players in worse condition back on their feet.
"Yesterday Zanetti arrived at the clinic and said he needed a tyre change. That's the kind of attitude he has."