Senators general manager Bryan Murray said it's too early to give a timeline for Spezza's return, but the team is hopeful he'll be play again this season.
"It's just the best thing to do at this point," Murray said Thursday at Scotiabank Place. "You probably could take days off and play a game here and there, but that doesn't make any sense for him or us. So getting it done, hopefully getting it cleaned out will allow him to come back at 100 percent and continue his career."
Spezza's back problems flared Sunday in a shootout loss to Pittsburgh. He missed the next two games, after contributing two goals and three assists in five games this season. He had 34 goals and 50 assists last season, finishing fourth in the NHL with 84 points.
"It's a big loss," Murray said. "The fortunate thing for us is we do have some people that play very hard on this team ... But we don't pretend we can replace that skill level."
Entering play Thursday night, Ottawa (5-1-1) and Boston shared first place in the Eastern Conference standings with 11 points each. The Bruins host the Buffalo Sabres on Thursday and the Senators play at Carolina on Friday.
The 29-year-old Spezza has 621 points (228-393) in 611 career regular-season games. He has 51 points (17-34) in 53 career playoff games.
Selected second overall in the 2001 draft, he's spent his entire career with the Senators.