The team made the announcement Saturday after offering no information on Green for the past week.
Green, 25, joined the Celtics last season as part of the trade that sent Kendrick Perkins to Oklahoma City. He averaged 9.8 points and 3.3 rebounds in 23.5 minutes per game in his 26 regular-season contests with Boston, and he saw action in nine playoff games.
The team said Green is expected to recover and be able to play in the 2012-13 season. Green’s surgery will take place on Jan. 9.
“While we are saddened that Jeff will not be able to play this season, the most important thing is his health, and we were fortunate to have access to an amazing team of specialists to evaluate Jeff’s case,” team president of basketball operations Danny Ainge said in a release. “The entire Celtics family supports Jeff during this difficult time in his career.”
Green signed a one-year deal with the Celtics last week, reportedly for $9 million. Shortly thereafter, he failed his physical, which kept him off the court for training camp.
The Mayo Clinic defines an aortic aneurysm as “a weakened and bulging area in the upper part of the aorta, the major blood vessel that feeds blood to the body,” with some cases requiring simple monitoring and others requiring surgery. It has no known causes, but it is more common in men than women.