The defenseman will be out for a second straight game, and for the 11th time in the past 12 games, when the Flyers host the Tampa Bay Lightning on Thursday (7 p.m. ET; SNE, SNO, SNP, NBCSP, BSSUN, ESPN+, NHL LIVE).
Ellis does not need surgery, coach Alain Vigneault said Thursday.
"My understanding is they're going to rehab and this is going to look like 4-6 weeks," Vigneault said. "That's what they're thinking about."
Ellis played 18:45 in a 5-2 loss to the Dallas Stars on Saturday, his first game after missing nine because of the injury.
"Everything was fine," Ellis said after that game. "Felt OK. Obviously it's tough when you miss hockey games and jump right back in, especially on a back to back where everyone is pretty tired (Flyers won 2-1 at the Carolina Hurricanes on Friday)."
Ellis, who was acquired in a trade with the Nashville Predators for forward Nolan Patrick and defenseman Philippe Myers on July 17, scored five points (one goal, four assists) and averaged 22:48 in ice time in four games.
Flyers forward Patrick Brown is considered week to week with a thumb injury sustained during the first period of a 2-1 overtime win against the Calgary Flames on Tuesday. Vigneault said Brown was meeting with doctors Thursday to determine how long he may be out.
