The Croatia international was subjected to a career-threatening tackle by Birmingham City defender Martin Taylor during last weekend's 2-2 draw.
The deadly challenge left Eduardo with a fractured left fibula and an open dislocation of his ankle joint.
Speculation surrounded the Brazilian-born striker's return date, with some suggesting that his career could be over.
However, the Gunners believe their injured forward could be back in action before 2009.
"All being well, Eduardo will have his leg in plaster and using crutches for the next six to eight weeks. After that time, partial weight-bearing exercises will be scheduled into a slow rehabilitation process," read an Arsenal statement.
"It is hoped that Eduardo will be running again in six months' time and making a full recovery after nine months."
Eduardo will miss Croatia's campaign for next year's Euro 2008 in Austria and Switzerland.