LeClair underwent tests Friday and must undergo surgery next Wednesday to repair his dislocated right shoulder suffered in Wednesday night's 7-2 loss to Pittsburgh.
"There was a tear in the labrum that can heal on its own. It's not a guarantee though, sometimes they pop back out," LeClair said. "We'll get it done (surgery), and hopefully it heals properly."
The injury occurred when LeClair was checked by defenseman Marc Bergevin and fell into the boards in the Penguins' zone with just over six minutes remaining in the first period.
"Johnny is an integral part of our team," Flyers captain Keith Primeau said. "He is a fantastic player and a great guy in the locker room. We have to be ready to play without him."
With just 16 goals in their last 12 contests, the Flyers will be hard-pressed to replace LeClair's team-leading 11 goals. On Friday, they were shut out for the second time in a week by the Toronto Maple Leafs, 3-0.
The Flyers also were missing Simon Gagne on Friday after the left wing injured his side against Pittsburgh. Gagne scored a career-high 33 goals last season but has only two in 21 games this campaign.
"We're just going to have to find some combinations we think work," Philadelphia Coach Ken Hitchcock said. "I don't think that you're going to get the offense to work with one person taking that role. It's going to take a lot more that that. We almost have to score by committee."
The 33-year-old LeClair has 352 career goals, including 303 in 560 games with the Flyers.