The team made the announcement Thursday, one day after officials determined Villanueva would miss the final few weeks of the season because of nagging tendinitis in his shoulder. Bucks center Andrew Bogut also will miss the rest of the season because of a sprained left foot.
Villanueva, the Bucks' major offseason acquisition, has been hampered by injuries all season and has played in only 39 games. He is scheduled to have the operation Tuesday in New York.
"It's more exploratory," general manager Larry Harris said Wednesday. "It could be a short amount of time. It could be a longer amount of time."