ENGLEWOOD—Jared Crick tried to fight the impossible fight.

His back wouldn’t come around, though, and the Broncos’ starting defensive end will need season-ending back surgery. The Broncos placed the defensive end on injured reserve and signed veteran nose tackle Ahtyba Rubin.

"It's business as usual because Jared hasn't been around the last month, but it's crappy when your boys go down. You feel for him,'' said Shelby Harris, who has essentially replaced Crick along with Adam Gotsis. "But in this business it doesn't stop. You've got to keep going. We're going to hold it down for him and allow for him to get himself right. That back stuff is nothing to play with. We just want him to get healthy. That's the type of injury where you realize there's more to life than just football.''

An overachiever who had 3.0 sacks and 15 starts for the Broncos last season, Crick was carted off the practice field Aug. 12 with a severe back injury.

He sat out three weeks, then tried returned to practice last week. But by Thursday, Crick had to rest again. He practiced again Wednesday but again he couldn’t go Thursday.

Crick, 28, is getting a second medical opinion from Dr. Robert Watkins but he has a disc issue that must be surgically repaired. The Broncos have already made an adjustment by signing Rubin, a former Cleveland Brown and Seattle Seahawk defensive tackle.

Rubin, 31, has been a starter since 2009. He is a 321-pound space eater who is athletic enough to register two interceptions and 15.0 sacks in his career. He was initially drafted in the sixth round out of Iowa State by the Browns in 2008. He was among the Seahawks' final cuts as they set their 53-man roster two weeks ago.

Because he's already in football shape, there is a 50-50 chance Rubin plays, if for only a few snaps, Sunday against Dallas.

“It was my first time going through a process like that and getting cut,'' said Rubin, who attended the Broncos' walkthrough practice Friday. "I don't really know what to expect. I was just sitting, waiting and staying in shape. My agents gave me hints on Buffalo and San Fran. Denver called me, I came here signed it and got it done. I'm more than thrilled to come here. I'm on a winning team, left another winning team to come to an even better team. I'm happy, I can't do anything but be ecstatic.”

Crick played at Nebraska and was the Houston Texans’ fourth-round draft pick in 2012. After four years in Houston, he became a free agent signed a two-year, $4 million contract with the Broncos. He will make $1.75 million this season, then become a free agent in March.