The Nerazzurri's "cursed" campaign looks set to continue until the final day of the season after the 30-year-old fell awkwardly in a routine practice session
The Italy international had only just returned to first-team action after a spell on the sidelines with a hamstring injury but he has now been ruled out of the Nerazzurri's final game of the season, against Udinese.
"Antonio Cassano underwent medical tests that were made necessary following a fall during the final game during training today," a statement on the club's official website read.
"Tests showed a fracture of the second metacarpal of the right hand."
Inter have been forced to make do without a number of key players this season, with Diego Milito, Rodrigo Palacio and Javier Zanetti among several players to have had their campaigns curtailed by injury.
Head coach Andrea Stramaccioni claimed last month that the San Siro side's season has been "cursed" after their Serie A and Europa League efforts were derailed by the loss of players.