He is expected to be ready for the start of the team's 2013-14 training camp later this year.
Sullinger, red-flagged before June's draft because of back issues, had been experiencing soreness before spasms chased him from Wednesday's win over the Sacramento Kings after four minutes of play. After undergoing tests on Thursday, the decision was made to fix the problem rather than attempt to manage the pain the rest of the season.
"We knew this could happen. We knew it a month before the draft that this could happen and at some point it probably would happen," Celtics coach Doc Rivers said. "We were hoping it would be a summer thing, rather than the middle of the season, but it happened now. He was playing great and the good news is we know he can play. We know he'll be a very good player and, in the long run, this will make him healthier."
Celtics president of basketball operations Danny Ainge admitted the news that Sullinger would require surgery came as a bit of a surprise, particularly on the heels of Sunday's news that Rajon Rondo had been lost for the season due to an ACL tear. But the team had braced itself for potential issues with Sullinger's back.
"I don't think it's out of the blue. He's been having some soreness," Ainge said. "I guess the fact that he had season-ending surgery was out of the blue. I don't think anybody thought that four or five days ago, but I think it's the best thing for Jared."
Later Ainge added: "The doctors feel like this is a great thing for Jared long term and that it's just frustrating that it hurts us here and now. In the long run, this is the best thing for Jared in his career."
Rivers noted that the team considers this a long-term fix, one that will hopefully limit Sullinger's back issues moving forward.
Both Ainge and Rivers were adamant that, even with the setback, they believe the team got a steal in the draft and someone who will help this franchise for a long time to come.
"Jared's disappointed of course," Ainge said. "He was having a great rookie year. He's been a very enthusiastic player on our team. He's a player who is well liked by his teammates and they believe in Jared. For a 20-year-old kid, his rebounding has been pretty special and it's been one of our weaknesses, so he's been a sight for sore eyes for our offensive rebounding and we're going to miss Jared."
Sullinger had been enjoying a fine rookie season, emerging as one of the Celtics' best rebounders and most consistent big men. Through 45 games, he boasted averages of six points and 5.9 rebounds in 19.8 minutes, while shooting 49.3 percent from the field. Those numbers had spiked in January, when he averaged seven points and 7.2 rebounds over 23.2 minutes per game while elevating to the starting lineup.
But the back flared, derailing his rookie season.
"It was definitely shocking. We didn't know how serious Sully's injury was when he left the game," said teammate Courtney Lee. "Actually, I didn't even know he left the game (on Wednesday). I went to the bench, but coming back they said his back just went out, so we were hoping that time would heal that. But then going into the next day he was in more pain and they came up with the conclusion that he has to have surgery. It's definitely a shocker for us."
Sullinger, initially pegged as a lottery pick in last June's draft, was medically red-flagged because of concerns over his back and slid to the Celtics, who selected him 21st overall out of Ohio State.
The news comes as another crushing blow to the Celtics, who lost All-Star Rondo for the season on Sunday when an MRI revealed the torn ACL, suffered in last Friday's double-overtime loss to the Atlanta Hawks.
"I mean, losing Rondo was big enough for us and now we're losing Sully, a guy that's one of our best rebounders on the team, especially on the offensive end," Lee said. "So with Rondo out, what we did is try to speed the tempo up and advance the ball up the floor with a pass to keep the tempo and the pace at the same level and then, with Sully, now we've all got to come together and guards have got to crack down and help the bigs rebound."
Brandon Bass will take Sullinger's place in the starting lineup and should see an increase in minutes. Boston also recalled its other first-round pick from last June's draft, Fab Melo, from the Maine Red Claws of the NBA Development League on Tuesday to receive treatment on an injured right quad. Rivers said Melo could stay with the parent club and see his first NBA action in limited minutes behind Bass, Kevin Garnett, Chris Wilcox and Jason Collins.
Despite the loss of Rondo and Sullinger, the Celtics believe they can remain a playoff contender moving forward.
"It's disappointing. Jared has had a terrific rookie year," Ainge said. "It's going to be tough, but we'll find another way to win. We're losing our best rebounder, but on the heels of the Rajon injury, it's extra tough I guess and we'll see how resilient we can be."
Ainge said the Celtics will add two more bodies before this month's trade deadline, but said he wants to remain patient and see how the team fares moving forward before deciding exactly how he will operate before the Feb. 21 trade deadline.
Rondo is seeking second opinions on his torn ACL, but the team hopes to have a date for his surgery early next week.
Boston had won two straight games without Rondo going into Friday's visit from the Orlando Magic.