Youkilis had missed eight of the past nine games because of what manager Joe Girardi had described as a stiff back. Youkilis played on Saturday, which cost the Yankees the opportunity to backdate his DL stint.
As a result, Youkilis won't be able to return until the middle of May. He could've been eligible to come off the disabled list more than a week earlier.
"You do the fire drill, you go through it, trainers, manager, coaches, player, doctor, everybody's involved, front office," Yankees general manager Brian Cashman said. "And if it works, you don't look back. If it doesn't work, you have regret. If we could do it all over again, we would not have played him last Saturday."
Cashman said that Youkilis received an epidural on Tuesday afternoon. Youkilis is not coming to Yankee Stadium -- the team told him to stay home and rest.
Youkilis, 34, will be replaced at third base by Jayson Nix. The Yankees called up rookie Corban Joseph, who has played mostly second in the minors but has some experience at third. He also played a couple of games at first base this season for Triple-A Scranton/Wilkes-Barre.
It's the first big league call-up for Joseph, 24, who was drafted by the Yankees in the fourth round of the 2008 amateur draft. In 22 games for Scranton/Wilkes-Barre, he was batting .273, with four homers and nine RBIs.
His Triple-A teammate and fellow infielder, David Adams, is batting .327 in 14 games for Scranton/Wilkes-Barre. But he is not eligible for a call-up until May 15 because he was released by the Yankees in late March and then re-signed.
ESPNNewYork.com's Kieran Darcy contributed to this report.