It appears Bills RT Chris Hairston will likely need ankle surgery. (US Presswire)

RT Chris Hairston’s season-ending ankle injury will likely require surgery, Buffalo Bills coach Chan Gailey said Thursday afternoon.

“It was one of those where they said it was a situation where he’s going to probably need surgery,” Gailey said. “They could have done something and maybe got him back for the last game or the next week, but it probably wouldn’t have happened that way.

“It was not ligament involved, it’s all [bone] involved. It was a bruise the other day but somehow I think there’s a loose body in there that they’ve got to take care of."

Hairston suffered the injury in Sunday’s 34-18 win over the Jacksonville Jaguars and was placed on injured reserve on Thursday morning.

It’s a tough break for the second-year pro. Hairston stepped into the starting lineup in Week 5 when Erik Pears was placed on IR and did a nice job with Pears out of the lineup.

Stevie Johnson makes it through practice: WR Stevie Johnson (left hamstring) was not full-go at Buffalo’s practice on Thursday, but he made it through the practice well after sitting out Wednesday’s session. “Stevie did most of practice, went through the whole thing and did OK,” Gailey said. “He was not full speed but he did OK, so that was a positive. It was good because he’d go out to practice and he’d sit on the bench just like he would in a game and would come back out and run and go sit on the bench. That was good. That activity was good.” Johnson has fought through injuries before and is expected to play Sunday against St. Louis.

OT Chris Scott added: With reinforcements needed along the offensive line, the Bills signed OT Chris Scott to the active roster. Scott joins the Bills off of Tennessee’s practice squad. He originally entered the NFL as a fifth-round pick of the Pittsburgh Steelers in 2010.

Arthur Moats back at DE: Arthur Moats has flipped back and forth between inside and outside linebacker more times than anyone can remember. In recent weeks, he’s moved back to his original position in the NFL -- DE, which is also where he played in college -- and he’s given the Bills’ injured defensive line a boost with limited reps. “We’ve been a little thin at defensive end and to give those guys a blow,” Gailey said. “And to be honest, the first time he went in there two weeks ago, he pushed the tackle right back into the quarterback and we remember what he did do when he was playing defensive end. It makes you remember those things, he’s been at linebacker so long. So he’s been a good change of pace to give us a little rest and give a little pressure to the quarterback.”

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