ORCHARD PARK — Things are finally looking up for the Bills injury-riddled defense, which might finally be getting some needed reinforcements.

After losing one starter after another, the Bills were buoyed after safety Donte Whitner and linebacker Paul Posluszny returned to practice Wednesday.

Posluszny is considered ahead of schedule after missing four games since breaking a bone in his left arm in Buffalo’s season-opening loss at New England. Whitner has missed two games since having surgery to repair torn tendons in his right thumb.

Both were cleared for practice on Tuesday and have a chance to play Sunday, when Buffalo (1-4) travels to face the New York Jets (3-2).

“I’m very hopeful. I wish I could have played last week,” Whitner said. “I’m excited to be back and I’ve been missing these guys.”

The feeling was certainly mutual.

“They couldn’t come back at a better time,” linebacker Keith Ellison said. “It’s a good feeling right now.”

It didn’t start out as a good week for the Bills, who placed linebackers Kawika Mitchell and Marcus Buggs on injured reserve after both sustained knee injuries in a 6-3 loss to Cleveland on Sunday.

Mitchell was hurt in his first game since being switched from the weak-side spot to start in the middle. Buggs was Mitchell’s backup, and had started in the middle the previous three games to fill in for Posluszny.

The injuries forced the Bills to scramble to sign two free agents, journeyman linebacker Chris Draft and safety Todd Johnson.

The defense is not the only unit dealing with injuries. Starting right tackle Jonathan Scott missed practice Wednesday after twisting his ankle last weekend. Slot receiver Josh Reed also missed practice because of a nagging leg injury.

Posluszny’s return would allow Ellison to remain at the strong-side linebacker position, while rookie Ashlee Palmer would start on the weak side.

Whitner’s return would bolster a backfield that’s still likely to be without starting strong safety Bryan Scott, who is expected to miss his third straight game with a sprained left ankle. The secondary is already missing starting cornerback Leodis McKelvin, who is out for the season with a broken leg.

Starting cornerback Terrence McGee was held out of practice Wednesday because of a nagging knee injury.

The injuries have particularly affected the Bills run defense. Buffalo’s allowed 643 yards rushing in its past three games.

The mere sight of Posluszny and Whitner back practicing gave the Bills a lift.

“Seeing those two guys come back, it was a big lift and a big confidence booster,” defensive tackle Marcus Stroud said. “It’s like being down to three in a five-man fight. Now you’ve got two more guys coming, so hopefully that’ll even up the odds.”