The Bruins’ 24th-ranked offense will likely be without its best scorer for the next two games.

On Friday, David Pastrnak had the bursa sac from his right elbow removed at Newton-Wellesley Hospital. Pastrnak (19 goals), second in the league behind Pittsburgh’s Sidney Crosby (21), is a good bet to be out of uniform until at least Thursday’s game against Florida.

“It’s never easy when you hear that kind of news on one of your better players this year,’’ said coach Claude Julien. “Those are challenges you have to face and get through. We’ll certainly do our best to get some wins here without him. Hopefully it’s shorter than longer.’’

Pastrnak landed five shots on net in Thursday’s 4-3 loss to Anaheim. He started the game on the No. 2 line with Tim Schaller and David Krejci. Pastrnak finished the night on the first line with Brad Marchand and Patrice Bergeron, his regular linemates.

It’s unknown who will play against Los Angeles on Sunday in Pastrnak’s top-line spot. The Bruins practiced with 11 forwards Saturday. Riley Nash was excused for personal reasons. David Backes practiced on the second line with Krejci and Ryan Spooner.

Backes missed five games after undergoing the same procedure in October. The right wing returned Nov. 5 against the Rangers. Backes was scoreless in his first three games after his absence.

“It’s not a fun little procedure he’s going through,’’ Backes said. “But he’s in the hands of great doctors. Hopefully he’ll be back sooner than I was. He’s a young 20-year-old kid that recovers pretty quick. With his energy and his drive, we expect him to be back in short order. Hopefully in less than a week, he’s back on the ice and scoring more goals for us.

“Just one of those things where it’s lightning striking twice in the same spot. You don’t expect it to happen once. Then twice in the same half of the season, that’s unfortunate.’’

Middle man

Austin Czarnik has been back in the middle for the last three games. It may be why the rookie is feeling better about his game.

“Coming back in the zone, it’s kind of a chip type of game or give it to someone else,’’ Czarnik said of playing right wing. “Now I can come back, hopefully get it a little more, and go.’’

Czarnik practiced on the No. 3 line Saturday between Schaller and Noel Acciari. All three can play the middle. But with Czarnik doing better offensive things with the puck, he’s gotten the nod to move back to center.

“We weren’t sure whether he could handle the wing. He has handled it, but he’s certainly been better up the middle,’’ Julien said. “You’ve got to be willing to play other positions when needed to, if you want to play in the NHL. If you can’t do it, then you find somebody else. Those guys have to understand that although they’re at a certain position, everybody on every team is asked to play different positions.’’

While Czarnik has moved back to center, it hasn’t been the case for some of his teammates. The Bruins have nine forwards who consider center their natural position: Czarnik, Krejci, Backes, Spooner, Nash, Bergeron, Schaller, Acciari, and Dominic Moore. Against Anaheim on Thursday, five of the natural centers played on the wing.

It is the most centers Julien has ever coached at one time. Julien prefers having more centers than fewer. It gives him options, especially on defensive-zone draws, when he likes having two centers available.

An overload of centers, however, can also cause players such as Czarnik to process the game differently when they’re on the wing. It’s not always easy. Star centers such as Bergeron, John Tavares, Joe Thornton, Steven Stamkos, Logan Couture, and Matt Duchene adjusted to the wing for Team Canada during the World Cup of Hockey. But they are go-to players because they can adapt to different situations.

“There’s no reason for a center not to be able to play the wing,’’ Julien said. “They may excel at center. But they can certainly play the wing, as well. That’s the situation we had at the World Cup. Those guys fared extremely well on the wing. There’s no reason for the guys, if they’re in that position, not to be able to do the same thing.’’

Solo skate

Joe Morrow didn’t practice with his teammates because of an undisclosed ailment. Morrow was healthy enough to skate on his own before the session. Morrow hasn’t played in the last two games but is available for Sunday’s matinee against the Kings . . . Frank Vatrano scored in Providence’s 3-2 win over Bridgeport on Friday. The left wing is likely to need another AHL tuneup before he’s brought back to the varsity. “You can skate all you want. It’s not game-type situations,’’ Julien said. “[Friday] night, I’m sure after the game he was exhausted. His first two periods were maybe a bit more of a struggle. He seemed to get a little better in the third. That’s an improvement. Hopefully we’re in a position to give him an opportunity to find his game. But with what’s going on right now, we don’t know what we’re going to end up doing.’’ . . . Defenseman Matt Grzelcyk was reassigned to Providence of the AHL. The former Boston University star made his NHL debut in Wednesday’s overtime loss to the Penguins, and also played Thursday against the Ducks.

Fluto Shinzawa can be reached at fshinzawa@globe.com. Follow him on Twitter @GlobeFluto.