Hunter is the team's third defensive lineman to suffer a serious injury at training camp in the past two years. Elvis Dumervil missed the 2010 season with a torn chest muscle and Ty Warren missed last season with a torn triceps.
Hunter had supplanted Robert Ayers as the starter at left end two weeks ago. He was replaced in the base defense Wednesday by rookie Derek Wolfe, the team's top draft choice who had two sacks at Chicago last week.
Wolfe had leaned on Hunter to help him get up to speed after missing all of the offseason workouts because of an NCAA rule that prevented him from joining his NFL teammates for workouts until his class had graduated from the University of Cincinnati.
Wolfe said he was bummed by Hunter's injury, but quickly added: "I've got to step in and do my job. There's no time to sit back and wallow in that. J-Hunt's one of my good friends, so I'd like to think of him as a mentor to me because he's been helping me out through this whole situation. I'm just going to step in there and do what I have to do."
Wolfe has drawn high praise from defensive coordinator Jack Del Rio for quickly getting up to speed.
"We couldn't do anything while I was out, so everybody had a couple of weeks and the whole spring on me, so I had to really grind when I got here," Wolfe said. "I had to stay and keep my nose in the playbook and I was sitting with (defensive line coach Jay) Rodgers and he'd have me write down every play. He's say the play and I'd write it down. We went through the whole playbook like that. It took us a couple of hours to get it."
Coach John Fox also said that right guard Chris Kuper is still expected to miss four to six weeks after having surgery on his broken left forearm.
Sixth-year pro Manny Ramirez took Kuper's spot in the lineup for most of the work with the first-team offense on Wednesday. Ramirez also lined up at center with right tackle Orlando Franklin sliding over to right guard and Chris Clark working at right tackle.
Kuper was working his way back from a gruesome injury in the Broncos' season finale on Jan. 1, when he dislocated his left ankle and sustained multiple breaks in his lower left fibula. He seemed to be making progress every day until he broke the ulna, the smaller of two bones, in his left forearm.
Hunter was having a terrific camp and brought so much passion to his new position on the depth chart that he was getting into almost daily scuffles with the offensive linemen.
But it was in hitting a blocking sled where he apparently got hurt Tuesday, the same day Kuper got hurt and rookie running back Ronnie Hillman aggravated his pulled right hamstring. Those injuries came a day after recently signed linebacker Keith Brooking (hamstring) got hurt.
Brooking will likely miss two weeks but his spot as a backup at weakside linebacker to Wesley Woodyard seems secure with starter D.J. Williams having to serve a six-game drug suspension to start the season.
Williams also might be facing further punishment from the league after being convicted Wednesday of driving while ability-impaired and driving without headlights in 2010.
NFL spokesman Greg Aiello said Williams' conviction "will be reviewed under our policies" to see if it merits further punishment.
Williams was expected to return to the Broncos for Thursday morning's practice while the NFL reviews the court's ruling. He hasn't gotten any work with the starters while awaiting his six-game suspension.
That will mark Peyton Manning's home debut for the Broncos after 14 seasons in Indianapolis. He's expected to play most of the first half after getting a dozen snaps in against Chicago in the preseason opener last week, his first game in 19 months.