The club also transferred right-hander Jordan Zimmermann to the 60-day disabled list, opening up a 40-man roster spot for Orr. Zimmermann underwent season-ending elbow surgery earlier this month and is expected to miss 12-18 months.
Morgan suffered his hand injury sliding head-first into third base against the Cubs on Thursday. At first, Morgan thought he dislocated his fingers and figured he would stay in the game. But he realized the injury was worse when he couldn't grip a bat.
"As soon as I hit the bag, I said, 'Oh, God.' I had so much adrenaline in me. I figured I could stay in the game," Morgan said. "I tried taping up the hand. I was being stubborn. I thought I could go back out there."
Morgan is expected to have surgery on the hand Saturday and is expected to recover in six weeks.
"I'm going to knock it all out so I could be ready for the 2010 season," Morgan said. "I'm only going to be out six weeks. I will be ready for Spring Training."
The hand injury cut short a season that had taken off since Morgan came to the Nationals in a trade from Pittsburgh on June 30. Morgan hit .351 with one homer, 12 RBIs and 24 steals for Washington.
"I'm patting myself on the back and congratulating myself on a fabulous year," Morgan said." I wish I could have finished strong. Once you start something, you always want to finish it."
As for Orr, this will be his second stint with the big club, his first this year. Last year, he played in 79 games and hit .253 with seven RBIs. Orr, 30, most likely will be used as a defensive replacement. Before the promotion, Orr was batting .245 with nine home runs and 50 RBIs for Syracuse.
"We wanted a left-handed bat off the bench," said Nationals general manager Mike Rizzo. "He gives us some versatility. He can pinch run, play the middle of the infield and can fill in in the outfield which he did in Triple-A."
Bill Ladson is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.