Julien explained the injury was the result of Boychuk's back "locking up" due to a muscle spasm after he was on the receiving end of boarding hit early in the first period of Thursday's 2-1 loss to the Montreal Canadiens at Bell Centre in Montreal.
He had to be helped off the ice on a stretcher.
If he continues to progress, it's possible he could miss only three to seven days.
"Johnny's doing better," Julien said. "We dodged a pretty good bullet there. Those kinds of injuries could have serious consequences. We feared the worst and we got as good of news as we could get.
"When he was down, he couldn't breathe. He couldn't move, either. On the medical side of it, our trainers, the Montreal doctors did the right thing. They took him off on a stretcher, took him to the hospital and got him checked out."
Prior to the injury, Boychuk had jumped into the rush and went to play the puck behind the Montreal net when he was hit by the Canadiens' Max Pacioretty at 4:28 of the first period. Boychuk was taken off the ice on a stretcher and transported to a nearby hospital to be examined by a specialist. He was then cleared to return to Boston with the team and reassessed by team doctors on Friday.
"We hope it will be a quicker recovery, kind of sooner than later kind of thing," Julien said. "It's hard to tell how long he's going to be out. He's still stiff this morning walking around. With those types of injuries, there's always that opportunity to spasm and the stiffness can go away quickly."
The Bruins held an optional skate Saturday morning as the team prepares to host the Pittsburgh Penguins at TD Garden. Boychuk will not play Saturday or Sunday at Toronto, but he will travel on the team's upcoming four-game road trip, according to Julien.
"It's a situation we'll see how it goes from there. His diagnosis was three to seven days," Julien said. "We're lucky and those kinds of injuries, back injuries, can have real serious consequences on the player's future. We dodged a bullet and we're happy about the fact it's a lot less severe than initially expected."
Boychuk has become a steady blueliner for the Bruins the last few seasons. He has one goal and five assists for six points, including a plus-8 rating this season.
Boychuk's teammates were thrilled to hear the news.
"Being one of the guys beside him on the ice, we were definitely concerned, knowing the type of guy Johnny is, he's never a guy that stays down unless he's seriously hurt," said teammate Milan Lucic. "Obviously, he was in a lot of pain that night and fortunately it's not too serious of an injury."