The injury will force Arenas to withdraw from contention for the 2006 World Championship team.
"We know Gilbert is really disappointed," said USA Basketball senior national team managing director Jerry Colangelo. "It's an unfortunate situation but he is not going to be able to continue on. This is a precautionary move but it is important that he return home and get treatment."
Arenas played in each of the four USA pre-World Championship games, averaging 3.8 points per game and 2.3 rebounds.
Team USA has won all four of its exhibition encounters and will conclude its exhibition schedule against Korea on Tuesday afternoon.
Preliminary games in the 2006 World Championship begin Saturday.