And so goes the last remaining member of the great Broncos draft class of 2006.

Chris Kuper, a mainstay on the Broncos’ offensive line since he was selected in the fifth round of that star-crossed 2006 class, is retiring after eight NFL seasons. Kuper was a starting guard from his second season of 2007 until he suffered a dislocated left ankle in the final game of the 2011 season.

Although he started five regular-season games, plus the playoff game in 2012 and in one more game last season, the ankle never healed to where Kuper could play at his past effectiveness.

“The season kind of furthered my idea that this would probably be the end for me,” Kuper said Monday at the Inverness Hotel in Englewood. “I didn’t feel good all season. I did my best when I was out there. I just wasn’t the same player. And I think that’s a big part of my decision, not being the same player.”

Kuper, 31, was part of the Broncos’ 2006 draft class that in terms of NFL production and star power might be the best in franchise history. It included quarterback Jay Cutler (first round), tight end Tony Scheffler (second), receiver Brandon Marshall (fourth), defensive end Elvis Dumervil (fourth), returner-receiver Domenik Hixon (fourth) and Kuper (fifth).

Kuper became the only one to play his entire career with the Broncos.

“But when you go back and look at the success that class had, when it was time for everyone to come into their contract years, it would have been hard to keep that group together,” Kuper said. “It would have been tough for us five guys to stick together, because the money wouldn’t have been there.”

Raised in Anchorage, Alaska, Kuper played his college ball at North Dakota, where he was a two-time Division II All-American. As a Broncos rookie, Kuper essentially redshirted behind starting guards Ben Hamilton and Cooper Carlisle, then moved in as a starter in 2007. Kuper emerged as one of the Broncos’ best blockers in 2008 and 2009 and was rewarded before the 2010 season with a five-year, $25.5 million contract extension.

Teammates picked him as a co- captain from 2010-12.

” ‘Kup’ consistently demonstrated the type of leadership you look for in a team captain,” Broncos coach John Fox said in a statement.

The devastating ankle injury occurred at the peak of Kuper’s play as he anchored an offensive line that helped Tim Tebow, Willis McGahee and the Broncos lead the league in rushing in 2011.

“I’m a little more proud of 2011 because it wasn’t really my style — I don’t think it’s anybody’s style anymore to run the ball that much — but there was a lot of stuff I had to work on to be successful that year,” Kuper said.

It was during a McGahee 6-yard run in the 2011 season finale against Kansas City that CBS cameras caught Kuper’s left ankle broken and dislocated to where it was almost turned backward.

After surgery, an infection set in. The plate holding the ankle together was shattered during the 2012 season. Kuper continued to play through that pain before he had another surgery last offseason to resolve the infection and hardware issues.