OKLAHOMA CITY – The Boston Celtics and Oklahoma City Thunder weren’t content with just being top-tier playoff contenders, swapping starters Thursday in a surprising deadline deal.

The Celtics sent center Kendrick Perkins to Oklahoma City and acquired forward Jeff Green and center Nenad Krstic, causing a shuffle in the frontcourt for the Thunder.

The Celtics also dealt reserve guard Nate Robinson to the Thunder and received a future first-round draft pick and cash in a deal that was approved by the NBA about five hours after the trade deadline.

Perkins recently returned from a knee injury sustained in Game 6 of the NBA finals. Once loaded with interior size, the Celtics will now have to hope Shaquille O’Neal and Jermaine O’Neal get healthy in time for the playoffs.

“They’re always looking toward the future,” said Chicago Bulls Coach Tom Thibodeau, a Boston assistant until last season. “Perkins did a lot for that team. He’s a very valuable player, he’s a great defensive player, and they got good players back for him. So I think it was a good trade for both teams.”

The Thunder parted with Green, who frequently played out of position at the power forward spot, and the 7-foot Krstic for the chance to get the key interior defender they had been lacking. Perkins was a vital part of the Celtics’ back-to-back trips to the NBA finals.

Green can be a backup at multiple positions and filled the void Boston created by trading away injured swingman Marquis Daniels to Sacramento.

Green’s production dropped off after he missed seven games early this season with a sprained left ankle, but he was starting to break out of it recently. He had been averaging just 13.7 points over a 29-game span, but topped 20 points in four of his last 10 games leading up to the trade deadline.

The inclusion of Krstic, the Thunder’s starting center since they brought him back to the NBA from Russia in December 2008, should help offset Boston’s loss of Perkins.