He has a contusion of his right ring finger.
Polanco suffered the injury on April 15 when he was hit by a pitch from Florida Marlins righthander Josh Beckett. He took batting practice before Wednesday's game against Colorado, and was placed on the DL following the contest.
"It's worse than yesterday," Polanco said after batting practice. "It stiffened because I hit and threw. It really hurts. I didn't want to (go on the DL). I was thinking about playing this weekend, then I hit (Tuesday) and it feels worse today. If I keep pushing, it's gonna get worse."
Complicating things for the second baseman is the fact that his elbow and shoulder began to hurt because he has been overcompensating his throwing motion to favor the tip of his right ring finger.
"We told him to shut it down until he was ready to throw and hit," said Philadelphia Manager Larry Bowa. "It's only April. He wants to play, but when you're talking about your hand and baseball, you do everything with that."
Polanco, acquired last season in the deal that sent Scott Rolen to St. Louis, shifted from third base to second base this season. He is batting .321 with one home run and five RBI in 14 games.
To fill Polanco's roster spot, the Phillies recalled second baseman Chase Utley from Triple-A Scranton/Wilkes-Barre of the International League.
He struck out as a pinch hitter in his only at-bat with the Phillies earlier this season before being sent to the minor leagues. On Wednesday, he went 0-for-4 against Buffalo, then boarded a plane to Philadelphia.
Utley was hitting .302 with one home run in 16 game with Scranton.