Bills CB Terrence McGee and RT Erik Pears rehabbed diligently throughout the first half of the season, missing practice after practice in order to try and make it for Sundays. Their seasons were shut down Tuesday when the Bills placed them on injured reserve, but their rehabilitation will continue. Coach Chan Gailey said Wednesday that both players would require additional surgery.

McGee fought his way back from offseason patella tendon surgery but was never able to get his left knee back to 100 percent. It’s believed that his current injury is not to the patella tendon, but is bad enough to require more surgery.

This injury could mark the end of McGee’s lengthy career with the Bills. A fourth-round pick back in 2003, McGee has ended three of the last four seasons on injured reserve and missed 20 games from 2009-2011. He played sparingly in seven games this season.

Asked if McGee’s future was in question, Gailey said it was too soon to tell.

“I think that all guys reach some point where they ask the question and you ask the question and you sit down and you see can a guy get healthy enough to help your football team? That’s a truism in our business," Gailey said. "There does come a time. Whether that’s Terrence’s time, I don’t know. I mean, let’s let him get completely well, see how he feels and make a decision when the time comes. But that’s not something ... we’re not even talking about that right now. I just want him to get well, see where he is as we go into next year.

Given all that he’s done to try and play in recent years, teammate Fred Jackson wouldn’t be surprised to see McGee give it another go next year. McGee has one year remaining on his contract.

“Without a doubt,” Jackson said. “I definitely would think he’s going to come back. ... He’s a fighter. He’ll keep working, get it taken care of and try to come back.”

Pears, meanwhile, has two years remaining on a contract extension he signed last season. The exact nature of his injury isn’t known, though it’s believed he had hernia surgery last offseason.

Johnson sits out: WR Stevie Johnson (thigh) was a notable non-participant at practice Wednesday. Gailey said that Johnson should be able to return Thursday. He suffered a thigh injury in Sunday’s loss to the Houston Texans. DE Mark Anderson (knee), CB Aaron Williams (knee) and DT Kyle Williams (ankle) also did not participate. DT Spencer Johnson (ankle) and RG Kraig Urbik (foot) were limited.

Two signed: After losing McGee and Pears for the season, the Bills added CB Crezdon Butler and OT Thomas Welch to the roster Wednesday. Butler entered the NFL as a fifth-round pick of the Pittsburgh Steelers in 2010 and most recently was on the Arizona Cardinals' practice squad. Welch was a seventh-round pick of the New England Patriots in 2010 and has also spent time in St. Louis and Minnesota.

“We had Thomas here earlier once before [for a visit] and liked him,” Gailey said. “We were hoping at some point to maybe get him back and it worked out that we did. We have had our eye on Crezdon Butler for a while now and [GM Buddy Nix] has always liked him. He’s a guy that we looked at a few weeks ago when Arizona let him go, we were trying to get him at that time but it didn’t work out. And now it worked out that we had a spot.”

For more updates on the Bills, follow correspondent Mark Ludwiczak on Twitter @CBSBills and@MarkLud12.